Determining the state of an ultrasonic end effector

ABSTRACT

Various systems and methods for determining the state of an end effector of an ultrasonic surgical instrument are disclosed. A control circuit can be configured to measure a complex impedance of an ultrasonic electromechanical system including an ultrasonic blade and compare the measured complex impedance to reference complex impedance patterns that each correspond to a state of the end effector. Accordingly, the control circuit can further be configured to determine the state of the end effector according to which of the plurality of reference complex impedance patterns the measured complex impedance corresponds.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Patent Application No. 62/721,996, titled RADIO FREQUENCYENERGY DEVICE FOR DELIVERING COMBINED ELECTRICAL SIGNALS, filed on Aug.23, 2018, the disclosure of which is herein incorporated by reference inits entirety.

The present application also claims priority under 35 U.S.C. § 119(e) toU.S. Provisional Patent Application No. 62/692,748, titled SMART ENERGYARCHITECTURE, filed on Jun. 30, 2018 and to U.S. Provisional PatentApplication No. 62/692,768, titled SMART ENERGY DEVICES, filed on Jun.30, 2018, the disclosure of each of which is herein incorporated byreference in its entirety.

This application also claims the benefit of priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 62/640,417,titled TEMPERATURE CONTROL IN ULTRASONIC DEVICE AND CONTROL SYSTEMTHEREFOR, filed Mar. 8, 2018, and to U.S. Provisional Patent ApplicationSer. No. 62/640,415, titled ESTIMATING STATE OF ULTRASONIC END EFFECTORAND CONTROL SYSTEM THEREFOR, filed Mar. 8, 2018, the disclosure of eachof which is herein incorporated by reference in its entirety.

This application also claims the benefit of priority under 35 U.S.C. §119(e) to U. S. Provisional Patent Application No. 62/650,898 filed onMar. 30, 2018, titled CAPACITIVE COUPLED RETURN PATH PAD WITH SEPARABLEARRAY ELEMENTS, the disclosure of which is herein incorporated byreference in its entirety.

BACKGROUND

In a surgical environment, smart energy devices may be needed in a smartenergy architecture environment.

SUMMARY

In one general aspect, an ultrasonic surgical instrument comprising: anend effector comprising an ultrasonic blade, an ultrasonic transduceracoustically coupled to the ultrasonic blade, and a control circuitcoupled to the ultrasonic transducer. The ultrasonic transducer isconfigured to ultrasonically oscillate the ultrasonic blade in responseto a drive signal. The control circuit is configured to: measure acomplex impedance of the ultrasonic transducer, compare the compleximpedance to a plurality of reference complex impedance patterns, eachof the plurality of reference complex impedance patterns correspondingto a state of the end effector, and determine the state of the endeffector according to which of the plurality of reference compleximpedance patterns the complex impedance corresponds.

In another general aspect, an ultrasonic generator for driving anultrasonic surgical instrument comprising an end effector, an ultrasonicblade, and an ultrasonic transducer acoustically coupled to theultrasonic blade. The ultrasonic transducer is configured toultrasonically oscillate the ultrasonic blade in response to a drivesignal. The ultrasonic generator comprises a control circuit coupled tothe ultrasonic transducer. The control circuit is configured to: applythe drive signal to the ultrasonic transducer, measure a compleximpedance of the ultrasonic transducer, compare the complex impedance toa plurality of reference complex impedance patterns, each of theplurality of reference complex impedance patterns corresponding to astate of the end effector, and determine the state of the end effectoraccording to which of the plurality of reference complex impedancepatterns the complex impedance corresponds.

In another general aspect, a method of controlling an ultrasonicsurgical instrument comprising an end effector, an ultrasonic blade, andan ultrasonic transducer acoustically coupled to the ultrasonic blade.The ultrasonic transducer is configured to ultrasonically oscillate theultrasonic blade in response to a drive signal from a generator. Themethod comprises: measuring, by a control circuit coupled to theultrasonic transducer, a complex impedance of the ultrasonic transducer;comparing, by the control circuit, the complex impedance to a pluralityof reference complex impedance patterns, each of the plurality ofreference complex impedance patterns corresponding to a state of the endeffector; and determining, by the control circuit, the state of the endeffector according to which of the plurality of reference compleximpedance patterns the complex impedance corresponds.

FIGURES

The features of various aspects are set forth with particularity in theappended claims. The various aspects, however, both as to organizationand methods of operation, together with further objects and advantagesthereof, may best be understood by reference to the followingdescription, taken in conjunction with the accompanying drawings asfollows.

FIG. 1 is a block diagram of a computer-implemented interactive surgicalsystem, in accordance with at least one aspect of the presentdisclosure.

FIG. 2 is a surgical system being used to perform a surgical procedurein an operating room, in accordance with at least one aspect of thepresent disclosure.

FIG. 3 is a surgical hub paired with a visualization system, a roboticsystem, and an intelligent instrument, in accordance with at least oneaspect of the present disclosure.

FIG. 4 is a partial perspective view of a surgical hub enclosure, and ofa combo generator module slidably receivable in a drawer of the surgicalhub enclosure, in accordance with at least one aspect of the presentdisclosure.

FIG. 5 is a perspective view of a combo generator module with bipolar,ultrasonic, and monopolar contacts and a smoke evacuation component, inaccordance with at least one aspect of the present disclosure.

FIG. 6 illustrates individual power bus attachments for a plurality oflateral docking ports of a lateral modular housing configured to receivea plurality of modules, in accordance with at least one aspect of thepresent disclosure.

FIG. 7 illustrates a vertical modular housing configured to receive aplurality of modules, in accordance with at least one aspect of thepresent disclosure.

FIG. 8 illustrates a surgical data network comprising a modularcommunication hub configured to connect modular devices located in oneor more operating theaters of a healthcare facility, or any room in ahealthcare facility specially equipped for surgical operations, to thecloud, in accordance with at least one aspect of the present disclosure.

FIG. 9 illustrates a computer-implemented interactive surgical system,in accordance with at least one aspect of the present disclosure.

FIG. 10 illustrates a surgical hub comprising a plurality of modulescoupled to the modular control tower, in accordance with at least oneaspect of the present disclosure.

FIG. 11 illustrates one aspect of a Universal Serial Bus (USB) networkhub device, in accordance with at least one aspect of the presentdisclosure.

FIG. 12 illustrates a logic diagram of a control system of a surgicalinstrument or tool, in accordance with at least one aspect of thepresent disclosure.

FIG. 13 illustrates a control circuit configured to control aspects ofthe surgical instrument or tool, in accordance with at least one aspectof the present disclosure.

FIG. 14 illustrates a combinational logic circuit configured to controlaspects of the surgical instrument or tool, in accordance with at leastone aspect of the present disclosure.

FIG. 15 illustrates a sequential logic circuit configured to controlaspects of the surgical instrument or tool, in accordance with at leastone aspect of the present disclosure.

FIG. 16 illustrates a surgical instrument or tool comprising a pluralityof motors which can be activated to perform various functions, inaccordance with at least one aspect of the present disclosure.

FIG. 17 is a schematic diagram of a robotic surgical instrumentconfigured to operate a surgical tool described herein, in accordancewith at least one aspect of the present disclosure.

FIG. 18 illustrates a block diagram of a surgical instrument programmedto control the distal translation of a displacement member, inaccordance with at least one aspect of the present disclosure.

FIG. 19 is a schematic diagram of a surgical instrument configured tocontrol various functions, in accordance with at least one aspect of thepresent disclosure.

FIG. 20 is a system configured to execute adaptive ultrasonic bladecontrol algorithms in a surgical data network comprising a modularcommunication hub, in accordance with at least one aspect of the presentdisclosure.

FIG. 21 illustrates an example of a generator, in accordance with atleast one aspect of the present disclosure.

FIG. 22 is a surgical system comprising a generator and various surgicalinstruments usable therewith, in accordance with at least one aspect ofthe present disclosure.

FIG. 23 is an end effector, in accordance with at least one aspect ofthe present disclosure.

FIG. 24 is a diagram of the surgical system of FIG. 22, in accordancewith at least one aspect of the present disclosure.

FIG. 25 is a model illustrating motional branch current, in accordancewith at least one aspect of the present disclosure.

FIG. 26 is a structural view of a generator architecture, in accordancewith at least one aspect of the present disclosure.

FIGS. 27A-27C are functional views of a generator architecture, inaccordance with at least one aspect of the present disclosure.

FIGS. 28A-28B are structural and functional aspects of a generator, inaccordance with at least one aspect of the present disclosure.

FIG. 29 is a schematic diagram of one aspect of an ultrasonic drivecircuit.

FIG. 30 is a schematic diagram of a control circuit, in accordance withat least one aspect of the present disclosure.

FIG. 31 shows a simplified block circuit diagram illustrating anotherelectrical circuit contained within a modular ultrasonic surgicalinstrument, in accordance with at least one aspect of the presentdisclosure.

FIG. 32 illustrates a generator circuit partitioned into multiplestages, in accordance with at least one aspect of the presentdisclosure.

FIG. 33 illustrates a generator circuit partitioned into multiple stageswhere a first stage circuit is common to the second stage circuit, inaccordance with at least one aspect of the present disclosure.

FIG. 34 is a schematic diagram of one aspect of a drive circuitconfigured for driving a high-frequency current (RF), in accordance withat least one aspect of the present disclosure.

FIG. 35 illustrates one aspect of a fundamental architecture for adigital synthesis circuit such as a direct digital synthesis (DDS)circuit configured to generate a plurality of wave shapes for theelectrical signal waveform for use in a surgical instrument, inaccordance with at least one aspect of the present disclosure.

FIG. 36 illustrates one aspect of direct digital synthesis (DDS) circuitconfigured to generate a plurality of wave shapes for the electricalsignal waveform for use in surgical instrument, in accordance with atleast one aspect of the present disclosure.

FIG. 37 illustrates one cycle of a discrete time digital electricalsignal waveform, in accordance with at least one aspect of the presentdisclosure of an analog waveform (shown superimposed over a discretetime digital electrical signal waveform for comparison purposes), inaccordance with at least one aspect of the present disclosure.

FIG. 38 is a diagram of a control system configured to provideprogressive closure of a closure member as it advances distally to closethe clamp arm to apply a closure force load at a desired rate accordingto one aspect of this disclosure.

FIG. 39 illustrates a proportional-integral-derivative (PID) controllerfeedback control system according to one aspect of this disclosure.

FIG. 40 is a system diagram of a segmented circuit comprising aplurality of independently operated circuit segments, in accordance withat least one aspect of the present disclosure.

FIG. 41 is a circuit diagram of various components of a surgicalinstrument with motor control functions, in accordance with at least oneaspect of the present disclosure.

FIG. 42 is an alternative system for controlling the frequency of anultrasonic electromechanical system and detecting the impedance thereof,in accordance with at least one aspect of the present disclosure.

FIG. 43A is a graphical representation of impedance phase angle as afunction of resonant frequency of the same ultrasonic device with a cold(blue) and hot (red) ultrasonic blade; and

FIG. 43B is a graphical representation of impedance magnitude as afunction of resonant frequency of the same ultrasonic device with a cold(blue) and hot (red) ultrasonic blade.

FIG. 44 is a diagram of a Kalman filter to improve temperature estimatorand state space model based on impedance across an ultrasonic transducermeasured at a variety of frequencies, in accordance with at least oneaspect of the present disclosure.

FIG. 45 are three probability distributions employed by a stateestimator of the Kalman filter shown in FIG. 44 to maximize estimates,in accordance with at least one aspect of the present disclosure.

FIG. 46A is a graphical representation of temperature versus time of anultrasonic device with no temperature control reaching a maximumtemperature of 490° C.

FIG. 46B is a graphical representation of temperature versus time of anultrasonic device with temperature control reaching a maximumtemperature of 320° C., in accordance with at least one aspect of thepresent disclosure.

FIGS. 47A-47B are graphical representations of feedback control toadjust ultrasonic power applied to an ultrasonic transducer when asudden drop in temperature of an ultrasonic blade is detected, where

FIG. 47A is a graphical representation of ultrasonic power as a functionof time; and

FIG. 47B is a plot of ultrasonic blade temperature as a function oftime, in accordance with at least one aspect of the present disclosure.

FIG. 48 is a logic flow diagram of a process depicting a control programor a logic configuration to control the temperature of an ultrasonicblade, in accordance with at least one aspect of the present disclosure.

FIG. 49 is a graphical representation of ultrasonic blade temperature asa function of time during a vessel firing, in accordance with at leastone aspect of the present disclosure.

FIG. 50 is a logic flow diagram of a process depicting a control programor a logic configuration to control the temperature of an ultrasonicblade between two temperature set points, in accordance with at leastone aspect of the present disclosure.

FIG. 51 is a logic flow diagram of a process depicting a control programor a logic configuration to determine the initial temperature of anultrasonic blade, in accordance with at least one aspect of the presentdisclosure.

FIG. 52 is a logic flow diagram of a process depicting a control programor a logic configuration to determine when an ultrasonic blade isapproaching instability and then adjusting the power to the ultrasonictransducer to prevent instability of the ultrasonic transducer, inaccordance with at least one aspect of the present disclosure.

FIG. 53 is a logic flow diagram of a process depicting a control programor a logic configuration to provide ultrasonic sealing with temperaturecontrol, in accordance with at least one aspect of the presentdisclosure.

FIG. 54 are graphical representations of ultrasonic transducer currentand ultrasonic blade temperature as a function of time, in accordancewith at least one aspect of the present disclosure.

FIG. 55 is a bottom view of an ultrasonic end effector showing a clamparm and ultrasonic blade delineating tissue positioning within theultrasonic end effector, in accordance with at least one aspect of thepresent disclosure.

FIG. 56 is a graphical representation depicting change in ultrasonictransducer impedance as a function tissue location within the ultrasonicend effector over a range of predetermined ultrasonic generator powerlevel increases, in accordance with at least one aspect of the presentdisclosure.

FIG. 57 is a graphical representation depicting change in ultrasonictransducer impedance as a function of time relative to the location oftissue within the ultrasonic end effector, in accordance with at leastone aspect of the present disclosure.

FIG. 58 is a logic flow diagram of a process depicting a control programor a logic configuration to identify operation in a non-therapeuticrange of power applied to the ultrasonic transducer to determine tissuepositioning, in accordance with at least one aspect of the presentdisclosure.

FIG. 59 illustrates one aspect of an end effector of an ultrasonicsurgical instrument comprising infrared (IR) sensors located on the jawmember, in accordance with at least one aspect of the presentdisclosure.

FIG. 60 illustrates one aspect of a flexible circuit on which the IRsensors shown in FIG. 59 may be mounted or formed integrally with, inaccordance to one aspect of the present disclosure.

FIG. 61 is a sectional view of an ultrasonic end effector comprising aclamp arm and an ultrasonic blade, in accordance with at least oneaspect of the present disclosure.

FIG. 62 illustrates IR refractivity detection sensor circuits mounted ona flexible circuit substrate shown in plan view, in accordance with atleast one aspect of the present disclosure.

FIG. 63 is a logic flow diagram of a process depicting a control programor a logic configuration to measure IR reflectance to determine tissuecomposition to tune the amplitude of the ultrasonic transducer, inaccordance with at least one aspect of the present disclosure.

FIG. 64A is a graphical representation of the rate of closure of theclamp arm versus time to identify the collagen transformation pointaccording to various aspects of the present disclosure where time isshown along the horizontal axis and change in clamp arm position isshown along the vertical axis, in accordance with at least one aspect ofthe present disclosure.

FIG. 64B is a magnified portion of the graphical representation shown inFIG. 64A.

FIG. 65 is a logic flow diagram of a process depicting a control programor a logic configuration to detect the collagen transformation point tocontrol the rate of closure of the of the clamp arm or the amplitude ofthe ultrasonic transducer, in accordance with at least one aspect of thepresent disclosure.

FIG. 66 is a graphical representation of the identification of thecollagen transformation temperature point to identify thecollagen/elastin ratio according to various aspects of the presentdisclosure, where tissue temperature is shown along the horizontal axisand ultrasonic transducer impedance is shown along the vertical axis, inaccordance with at least one aspect of the present disclosure.

FIG. 67 is a logic flow diagram of a process depicting a control programor a logic configuration to identify the collagen transformationtemperature to identify the collagen/elastin ratio, in accordance withat least one aspect of the present disclosure.

FIG. 68 is a graphical representation of the distribution of compressionload across an ultrasonic blade, in accordance with at least one aspectof the present disclosure.

FIG. 69 is a graphical representation of pressure applied to tissueversus time, in accordance with at least one aspect of the presentdisclosure.

FIG. 70 illustrates an end effector including a single-jaw electrodearray for detecting tissue location, in accordance with at least oneaspect of the present disclosure.

FIG. 71 is an activation matrix for the single-jaw electrode array ofFIG. 70, in accordance with at least one aspect of the presentdisclosure.

FIG. 72 illustrates an end effector including a dual-jaw electrode arrayfor detecting tissue location, in accordance with at least one aspect ofthe present disclosure.

FIG. 73 is an activation matrix for the dual-jaw electrode array of FIG.72, in accordance with at least one aspect of the present disclosure.

FIG. 74 illustrates opposing sets of electrodes overlaid a tissuegrasped by an end effector corresponding to the activation matrix onFIG. 73, in accordance with at least one aspect of the presentdisclosure.

FIG. 75 illustrates an end effector including dual-jaw segmentedelectrode array, according to at least one aspect of the presentdisclosure.

FIG. 76 illustrates a tissue overlaid a jaw including a segmentedelectrode array, according to at least one aspect of the presentdisclosure.

FIG. 77 is a schematic diagram of a segmented electrode array circuitincluding band-pass filters, in accordance with at least one aspect ofthe present disclosure.

FIG. 78 is a graphical representation of the frequency responsecorresponding to the tissue grasped in FIG. 76, in accordance with atleast one aspect of the present disclosure.

FIG. 79 is a graphical representation of the frequency of the ultrasonictransducer system as a function of drive frequency and ultrasonic bladetemperature drift, in accordance with at least one aspect of the presentdisclosure.

FIG. 80 is a graphical representation of temperature of the ultrasonictransducer as a function of time, in accordance with at least one aspectof the present disclosure.

FIG. 81 is a graphical representation of the modal shift of resonantfrequency based on the temperature of the ultrasonic blade moving theresonant frequency as a function of the temperature of the ultrasonicblade, in accordance with at least one aspect of the present disclosure.

FIG. 82 is a spectra of an ultrasonic surgical instrument with a varietyof different states and conditions of the end effector where phase andmagnitude of the impedance of an ultrasonic transducer are plotted as afunction of frequency, in accordance with at least one aspect of thepresent disclosure.

FIG. 83 is a methodology for classification of data based on a set oftraining data S, where ultrasonic transducer impedance magnitude andphase are plotted as a function of frequency, in accordance with atleast one aspect of the present disclosure.

FIG. 84 is a logic flow diagram depicting a control program or a logicconfiguration to determine jaw conditions based on the complex impedancecharacteristic pattern (fingerprint), in accordance with at least oneaspect of the present disclosure.

FIG. 85 is a timeline depicting situational awareness of a surgical hub,in accordance with at least one aspect of the present disclosure.

DESCRIPTION

Applicant of the present application owns the following U.S. PatentApplications, filed on Aug. 28, 2018, the disclosure of each of which isherein incorporated by reference in its entirety:

-   -   U.S. Patent Application Docket No. END8536USNP2/180107-2, titled        ESTIMATING STATE OF ULTRASONIC END EFFECTOR AND CONTROL SYSTEM        THEREFOR;    -   U.S. Patent Application Docket No. END8560USNP2/180106-2, titled        TEMPERATURE CONTROL OF ULTRASONIC END EFFECTOR AND CONTROL        SYSTEM THEREFOR;    -   U.S. Patent Application Docket No. END8561USNP1/180144-1, titled        RADIO FREQUENCY ENERGY DEVICE FOR DELIVERING COMBINED ELECTRICAL        SIGNALS;    -   U.S. Patent Application Docket No. END8563USNP1/180139-1, titled        CONTROLLING AN ULTRASONIC SURGICAL INSTRUMENT ACCORDING TO        TISSUE LOCATION;    -   U.S. Patent Application Docket No. END8563USNP2/180139-2, titled        CONTROLLING ACTIVATION OF AN ULTRASONIC SURGICAL INSTRUMENT        ACCORDING TO THE PRESENCE OF TISSUE;    -   U.S. Patent Application Docket No. END8563USNP3/180139-3, titled        DETERMINING TISSUE COMPOSITION VIA AN ULTRASONIC SYSTEM;    -   U.S. Patent Application Docket No. END8563USNP4/180139-4, titled        DETERMINING THE STATE OF AN ULTRASONIC ELECTROMECHANICAL SYSTEM        ACCORDING TO FREQUENCY SHIFT;    -   U.S. Patent Application Docket No. END8564USNP1/180140-1, titled        SITUATIONAL AWARENESS OF ELECTROSURGICAL SYSTEMS;    -   U.S. Patent Application Docket No. END8564USNP2/180140-2, titled        MECHANISMS FOR CONTROLLING DIFFERENT ELECTROMECHANICAL SYSTEMS        OF AN ELECTROSURGICAL INSTRUMENT;    -   U.S. Patent Application Docket No. END8564USNP3/180140-3, titled        DETECTION OF END EFFECTOR IMMERSION IN LIQUID;    -   U.S. Patent Application Docket No. END8565USNP1/180142-1, titled        INTERRUPTION OF ENERGY DUE TO INADVERTENT CAPACITIVE COUPLING;    -   U.S. Patent Application Docket No. END8565USNP2/180142-2, titled        INCREASING RADIO FREQUENCY TO CREATE PAD-LESS MONOPOLAR LOOP;    -   U.S. Patent Application Docket No. END8566USNP1/180143-1, titled        BIPOLAR COMBINATION DEVICE THAT AUTOMATICALLY ADJUSTS PRESSURE        BASED ON ENERGY MODALITY; and    -   U.S. Patent Application Docket No. END8573USNP1/180145-1, titled        ACTIVATION OF ENERGY DEVICES.

Applicant of the present application owns the following U.S. PatentApplications, filed on Aug. 23, 2018, the disclosure of each of which isherein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application No. 62/721,995, titled        CONTROLLING AN ULTRASONIC SURGICAL INSTRUMENT ACCORDING TO        TISSUE LOCATION;    -   U.S. Provisional Patent Application No. 62/721,998, titled        SITUATIONAL AWARENESS OF ELECTROSURGICAL SYSTEMS;    -   U.S. Provisional Patent Application No. 62/721,999, titled        INTERRUPTION OF ENERGY DUE TO INADVERTENT CAPACITIVE COUPLING;    -   U.S. Provisional Patent Application No. 62/721,994, titled        BIPOLAR COMBINATION DEVICE THAT AUTOMATICALLY ADJUSTS PRESSURE        BASED ON ENERGY MODALITY; and    -   U.S. Provisional Patent Application No. 62/721,996, titled RADIO        FREQUENCY ENERGY DEVICE FOR DELIVERING COMBINED ELECTRICAL        SIGNALS.

Applicant of the present application owns the following U.S. PatentApplications, filed on Jun. 30, 2018, the disclosure of each of which isherein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application No. 62/692,747, titled SMART        ACTIVATION OF AN ENERGY DEVICE BY ANOTHER DEVICE;    -   U.S. Provisional Patent Application No. 62/692,748, titled SMART        ENERGY ARCHITECTURE; and    -   U.S. Provisional Patent Application No. 62/692,768, titled SMART        ENERGY DEVICES.

Applicant of the present application owns the following U.S. PatentApplications, filed on Jun. 29, 2018, the disclosure of each of which isherein incorporated by reference in its entirety:

-   -   U.S. patent application Ser. No. 16/024,090, titled CAPACITIVE        COUPLED RETURN PATH PAD WITH SEPARABLE ARRAY ELEMENTS;    -   U.S. patent application Ser. No. 16/024,057, titled CONTROLLING        A SURGICAL INSTRUMENT ACCORDING TO SENSED CLOSURE PARAMETERS;    -   U.S. patent application Ser. No. 16/024,067, titled SYSTEMS FOR        ADJUSTING END EFFECTOR PARAMETERS BASED ON PERIOPERATIVE        INFORMATION;    -   U.S. patent application Ser. No. 16/024,075, titled SAFETY        SYSTEMS FOR SMART POWERED SURGICAL STAPLING;    -   U.S. patent application Ser. No. 16/024,083, titled SAFETY        SYSTEMS FOR SMART POWERED SURGICAL STAPLING;    -   U.S. patent application Ser. No. 16/024,094, titled SURGICAL        SYSTEMS FOR DETECTING END EFFECTOR TISSUE DISTRIBUTION        IRREGULARITIES;    -   U.S. patent application Ser. No. 16/024,138, titled SYSTEMS FOR        DETECTING PROXIMITY OF SURGICAL END EFFECTOR TO CANCEROUS        TISSUE;    -   U.S. patent application Ser. No. 16/024,150, titled SURGICAL        INSTRUMENT CARTRIDGE SENSOR ASSEMBLIES;    -   U.S. patent application Ser. No. 16/024,160, titled VARIABLE        OUTPUT CARTRIDGE SENSOR ASSEMBLY;    -   U.S. patent application Ser. No. 16/024,124, titled SURGICAL        INSTRUMENT HAVING A FLEXIBLE ELECTRODE;    -   U.S. patent application Ser. No. 16/024,132, titled SURGICAL        INSTRUMENT HAVING A FLEXIBLE CIRCUIT;    -   U.S. patent application Ser. No. 16/024,141, titled SURGICAL        INSTRUMENT WITH A TISSUE MARKING ASSEMBLY;    -   U.S. patent application Ser. No. 16/024,162, titled SURGICAL        SYSTEMS WITH PRIORITIZED DATA TRANSMISSION CAPABILITIES;    -   U.S. patent application Ser. No. 16/024,066, titled SURGICAL        EVACUATION SENSING AND MOTOR CONTROL;    -   U.S. patent application Ser. No. 16/024,096, titled SURGICAL        EVACUATION SENSOR ARRANGEMENTS;    -   U.S. patent application Ser. No. 16/024,116, titled SURGICAL        EVACUATION FLOW PATHS;    -   U.S. patent application Ser. No. 16/024,149, titled SURGICAL        EVACUATION SENSING AND GENERATOR CONTROL;    -   U.S. patent application Ser. No. 16/024,180, titled SURGICAL        EVACUATION SENSING AND DISPLAY;    -   U.S. patent application Ser. No. 16/024,245, titled        COMMUNICATION OF SMOKE EVACUATION SYSTEM PARAMETERS TO HUB OR        CLOUD IN SMOKE EVACUATION MODULE FOR INTERACTIVE SURGICAL        PLATFORM;    -   U.S. patent application Ser. No. 16/024,258, titled SMOKE        EVACUATION SYSTEM INCLUDING A SEGMENTED CONTROL CIRCUIT FOR        INTERACTIVE SURGICAL PLATFORM;    -   U.S. patent application Ser. No. 16/024,265, titled SURGICAL        EVACUATION SYSTEM WITH A COMMUNICATION CIRCUIT FOR COMMUNICATION        BETWEEN A FILTER AND A SMOKE EVACUATION DEVICE; and    -   U.S. patent application Ser. No. 16/024,273, titled DUAL        IN-SERIES LARGE AND SMALL DROPLET FILTERS.

Applicant of the present application owns the following U.S. ProvisionalPatent Applications, filed on Jun. 28, 2018, the disclosure of each ofwhich is herein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application Ser. No. 62/691,228, titled        A METHOD OF USING REINFORCED FLEX CIRCUITS WITH MULTIPLE SENSORS        WITH ELECTROSURGICAL DEVICES;    -   U.S. Provisional Patent Application Ser. No. 62/691,227, titled        CONTROLLING A SURGICAL INSTRUMENT ACCORDING TO SENSED CLOSURE        PARAMETERS;    -   U.S. Provisional Patent Application Ser. No. 62/691,230, titled        SURGICAL INSTRUMENT HAVING A FLEXIBLE ELECTRODE;    -   U.S. Provisional Patent Application Ser. No. 62/691,219, titled        SURGICAL EVACUATION SENSING AND MOTOR CONTROL;    -   U.S. Provisional Patent Application Ser. No. 62/691,257, titled        COMMUNICATION OF SMOKE EVACUATION SYSTEM PARAMETERS TO HUB OR        CLOUD IN SMOKE EVACUATION MODULE FOR INTERACTIVE SURGICAL        PLATFORM;    -   U.S. Provisional Patent Application Ser. No. 62/691,262, titled        SURGICAL EVACUATION SYSTEM WITH A COMMUNICATION CIRCUIT FOR        COMMUNICATION BETWEEN A FILTER AND A SMOKE EVACUATION DEVICE;        and    -   U.S. Provisional Patent Application Ser. No. 62/691,251, titled        DUAL IN-SERIES LARGE AND SMALL DROPLET FILTERS.

Applicant of the present application owns the following U.S. ProvisionalPatent Application, filed on Apr. 19, 2018, the disclosure of each ofwhich is herein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application Ser. No. 62/659,900, titled        METHOD OF HUB COMMUNICATION.

Applicant of the present application owns the following U.S. ProvisionalPatent Applications, filed on Mar. 30, 2018, the disclosure of each ofwhich is herein incorporated by reference in its entirety:

-   -   U. S. Provisional Patent Application No. 62/650,898 filed on        Mar. 30, 2018, titled CAPACITIVE COUPLED RETURN PATH PAD WITH        SEPARABLE ARRAY ELEMENTS;    -   U.S. Provisional Patent Application Ser. No. 62/650,887, titled        SURGICAL SYSTEMS WITH OPTIMIZED SENSING CAPABILITIES;    -   U.S. Provisional Patent Application Ser. No. 62/650,882, titled        SMOKE EVACUATION MODULE FOR INTERACTIVE SURGICAL PLATFORM; and    -   U.S. Provisional Patent Application Ser. No. 62/650,877, titled        SURGICAL SMOKE EVACUATION SENSING AND CONTROLS

Applicant of the present application owns the following U.S. PatentApplications, filed on Mar. 29, 2018, the disclosure of each of which isherein incorporated by reference in its entirety:

-   -   U.S. patent application Ser. No. 15/940,641, titled INTERACTIVE        SURGICAL SYSTEMS WITH ENCRYPTED COMMUNICATION CAPABILITIES;    -   U.S. patent application Ser. No. 15/940,648, titled INTERACTIVE        SURGICAL SYSTEMS WITH CONDITION HANDLING OF DEVICES AND DATA        CAPABILITIES;    -   U.S. patent application Ser. No. 15/940,656, titled SURGICAL HUB        COORDINATION OF CONTROL AND COMMUNICATION OF OPERATING ROOM        DEVICES;    -   U.S. patent application Ser. No. 15/940,666, titled SPATIAL        AWARENESS OF SURGICAL HUBS IN OPERATING ROOMS;    -   U.S. patent application Ser. No. 15/940,670, titled COOPERATIVE        UTILIZATION OF DATA DERIVED FROM SECONDARY SOURCES BY        INTELLIGENT SURGICAL HUBS;    -   U.S. patent application Ser. No. 15/940,677, titled SURGICAL HUB        CONTROL ARRANGEMENTS;    -   U.S. patent application Ser. No. 15/940,632, titled DATA        STRIPPING METHOD TO INTERROGATE PATIENT RECORDS AND CREATE        ANONYMIZED RECORD;    -   U.S. patent application Ser. No. 15/940,640, titled        COMMUNICATION HUB AND STORAGE DEVICE FOR STORING PARAMETERS AND        STATUS OF A SURGICAL DEVICE TO BE SHARED WITH CLOUD BASED        ANALYTICS SYSTEMS;    -   U.S. patent application Ser. No. 15/940,645, titled SELF        DESCRIBING DATA PACKETS GENERATED AT AN ISSUING INSTRUMENT;    -   U.S. patent application Ser. No. 15/940,649, titled DATA PAIRING        TO INTERCONNECT A DEVICE MEASURED PARAMETER WITH AN OUTCOME;    -   U.S. patent application Ser. No. 15/940,654, titled SURGICAL HUB        SITUATIONAL AWARENESS;    -   U.S. patent application Ser. No. 15/940,663, titled SURGICAL        SYSTEM DISTRIBUTED PROCESSING;    -   U.S. patent application Ser. No. 15/940,668, titled AGGREGATION        AND REPORTING OF SURGICAL HUB DATA;    -   U.S. patent application Ser. No. 15/940,671, titled SURGICAL HUB        SPATIAL AWARENESS TO DETERMINE DEVICES IN OPERATING THEATER;    -   U.S. patent application Ser. No. 15/940,686, titled DISPLAY OF        ALIGNMENT OF STAPLE CARTRIDGE TO PRIOR LINEAR STAPLE LINE;    -   U.S. patent application Ser. No. 15/940,700, titled STERILE        FIELD INTERACTIVE CONTROL DISPLAYS;    -   U.S. patent application Ser. No. 15/940,629, titled COMPUTER        IMPLEMENTED INTERACTIVE SURGICAL SYSTEMS;    -   U.S. patent application Ser. No. 15/940,704, titled USE OF LASER        LIGHT AND RED-GREEN-BLUE COLORATION TO DETERMINE PROPERTIES OF        BACK SCATTERED LIGHT;    -   U.S. patent application Ser. No. 15/940,722, titled        CHARACTERIZATION OF TISSUE IRREGULARITIES THROUGH THE USE OF        MONO-CHROMATIC LIGHT REFRACTIVITY; and    -   U.S. patent application Ser. No. 15/940,742, titled DUAL CMOS        ARRAY IMAGING.    -   U.S. patent application Ser. No. 15/940,636, titled ADAPTIVE        CONTROL PROGRAM UPDATES FOR SURGICAL DEVICES;    -   U.S. patent application Ser. No. 15/940,653, titled ADAPTIVE        CONTROL PROGRAM UPDATES FOR SURGICAL HUBS;    -   U.S. patent application Ser. No. 15/940,660, titled CLOUD-BASED        MEDICAL ANALYTICS FOR CUSTOMIZATION AND RECOMMENDATIONS TO A        USER;    -   U.S. patent application Ser. No. 15/940,679, titled CLOUD-BASED        MEDICAL ANALYTICS FOR LINKING OF LOCAL USAGE TRENDS WITH THE        RESOURCE ACQUISITION BEHAVIORS OF LARGER DATA SET;    -   U.S. patent application Ser. No. 15/940,694, titled CLOUD-BASED        MEDICAL ANALYTICS FOR MEDICAL FACILITY SEGMENTED        INDIVIDUALIZATION OF INSTRUMENT FUNCTION;    -   U.S. patent application Ser. No. 15/940,634, titled CLOUD-BASED        MEDICAL ANALYTICS FOR SECURITY AND AUTHENTICATION TRENDS AND        REACTIVE MEASURES;    -   U.S. patent application Ser. No. 15/940,706, titled DATA        HANDLING AND PRIORITIZATION IN A CLOUD ANALYTICS NETWORK; and    -   U.S. patent application Ser. No. 15/940,675, titled CLOUD        INTERFACE FOR COUPLED SURGICAL DEVICES.    -   U.S. patent application Ser. No. 15/940,627, titled DRIVE        ARRANGEMENTS FOR ROBOT-ASSISTED SURGICAL PLATFORMS;    -   U.S. patent application Ser. No. 15/940,637, titled        COMMUNICATION ARRANGEMENTS FOR ROBOT-ASSISTED SURGICAL        PLATFORMS;    -   U.S. patent application Ser. No. 15/940,642, titled CONTROLS FOR        ROBOT-ASSISTED SURGICAL PLATFORMS;    -   U.S. patent application Ser. No. 15/940,676, titled AUTOMATIC        TOOL ADJUSTMENTS FOR ROBOT-ASSISTED SURGICAL PLATFORMS;    -   U.S. patent application Ser. No. 15/940,680, titled CONTROLLERS        FOR ROBOT-ASSISTED SURGICAL PLATFORMS;    -   U.S. patent application Ser. No. 15/940,683, titled COOPERATIVE        SURGICAL ACTIONS FOR ROBOT-ASSISTED SURGICAL PLATFORMS;    -   U.S. patent application Ser. No. 15/940,690, titled DISPLAY        ARRANGEMENTS FOR ROBOT-ASSISTED SURGICAL PLATFORMS; and    -   U.S. patent application Ser. No. 15/940,711, titled SENSING        ARRANGEMENTS FOR ROBOT-ASSISTED SURGICAL PLATFORMS.

Applicant of the present application owns the following U.S. ProvisionalPatent Applications, filed on Mar. 28, 2018, the disclosure of each ofwhich is herein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application Ser. No. 62/649,302, titled        INTERACTIVE SURGICAL SYSTEMS WITH ENCRYPTED COMMUNICATION        CAPABILITIES;    -   U.S. Provisional Patent Application Ser. No. 62/649,294, titled        DATA STRIPPING METHOD TO INTERROGATE PATIENT RECORDS AND CREATE        ANONYMIZED RECORD;    -   U.S. Provisional Patent Application Ser. No. 62/649,300, titled        SURGICAL HUB SITUATIONAL AWARENESS;    -   U.S. Provisional Patent Application Ser. No. 62/649,309, titled        SURGICAL HUB SPATIAL AWARENESS TO DETERMINE DEVICES IN OPERATING        THEATER;    -   U.S. Provisional Patent Application Ser. No. 62/649,310, titled        COMPUTER IMPLEMENTED INTERACTIVE SURGICAL SYSTEMS;    -   U.S. Provisional Patent Application Ser. No. 62/649,291, titled        USE OF LASER LIGHT AND RED-GREEN-BLUE COLORATION TO DETERMINE        PROPERTIES OF BACK SCATTERED LIGHT;    -   U.S. Provisional Patent Application Ser. No. 62/649,296, titled        ADAPTIVE CONTROL PROGRAM UPDATES FOR SURGICAL DEVICES;    -   U.S. Provisional Patent Application Ser. No. 62/649,333, titled        CLOUD-BASED MEDICAL ANALYTICS FOR CUSTOMIZATION AND        RECOMMENDATIONS TO A USER;    -   U.S. Provisional Patent Application Ser. No. 62/649,327, titled        CLOUD-BASED MEDICAL ANALYTICS FOR SECURITY AND AUTHENTICATION        TRENDS AND REACTIVE MEASURES;    -   U.S. Provisional Patent Application Ser. No. 62/649,315, titled        DATA HANDLING AND PRIORITIZATION IN A CLOUD ANALYTICS NETWORK;    -   U.S. Provisional Patent Application Ser. No. 62/649,313, titled        CLOUD INTERFACE FOR COUPLED SURGICAL DEVICES;    -   U.S. Provisional Patent Application Ser. No. 62/649,320, titled        DRIVE ARRANGEMENTS FOR ROBOT-ASSISTED SURGICAL PLATFORMS;    -   U.S. Provisional Patent Application Ser. No. 62/649,307, titled        AUTOMATIC TOOL ADJUSTMENTS FOR ROBOT-ASSISTED SURGICAL        PLATFORMS; and    -   U.S. Provisional Patent Application Ser. No. 62/649,323, titled        SENSING ARRANGEMENTS FOR ROBOT-ASSISTED SURGICAL PLATFORMS.

Applicant of the present application owns the following U.S. ProvisionalPatent Applications, filed on Mar. 8, 2018, the disclosure of each ofwhich is herein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application Ser. No. 62/640,417, titled        TEMPERATURE CONTROL IN ULTRASONIC DEVICE AND CONTROL SYSTEM        THEREFOR; and    -   U. S. Provisional Patent Application Ser. No. 62/640,415, titled        ESTIMATING STATE OF ULTRASONIC END EFFECTOR AND CONTROL SYSTEM        THEREFOR.

Applicant of the present application owns the following U.S. ProvisionalPatent Applications, filed on Dec. 28, 2017, the disclosure of each ofwhich is herein incorporated by reference in its entirety:

-   -   U.S. Provisional Patent Application Serial No. U.S. Provisional        Patent Application Ser. No. 62/611,341, titled INTERACTIVE        SURGICAL PLATFORM;    -   U.S. Provisional Patent Application Ser. No. 62/611,340, titled        CLOUD-BASED MEDICAL ANALYTICS; and    -   U.S. Provisional Patent Application Ser. No. 62/611,339, titled        ROBOT ASSISTED SURGICAL PLATFORM.

Before explaining various aspects of surgical devices and generators indetail, it should be noted that the illustrative examples are notlimited in application or use to the details of construction andarrangement of parts illustrated in the accompanying drawings anddescription. The illustrative examples may be implemented orincorporated in other aspects, variations and modifications, and may bepracticed or carried out in various ways. Further, unless otherwiseindicated, the terms and expressions employed herein have been chosenfor the purpose of describing the illustrative examples for theconvenience of the reader and are not for the purpose of limitationthereof. Also, it will be appreciated that one or more of thefollowing-described aspects, expressions of aspects, and/or examples,can be combined with any one or more of the other following-describedaspects, expressions of aspects and/or examples.

Various aspects are directed to improved ultrasonic surgical devices,electrosurgical devices and generators for use therewith. Aspects of theultrasonic surgical devices can be configured for transecting and/orcoagulating tissue during surgical procedures, for example. Aspects ofthe electrosurgical devices can be configured for transecting,coagulating, scaling, welding and/or desiccating tissue during surgicalprocedures, for example.

Referring to FIG. 1, a computer-implemented interactive surgical system100 includes one or more surgical systems 102 and a cloud-based system(e.g., the cloud 104 that may include a remote server 113 coupled to astorage device 105). Each surgical system 102 includes at least onesurgical hub 106 in communication with the cloud 104 that may include aremote server 113. In one example, as illustrated in FIG. 1, thesurgical system 102 includes a visualization system 108, a roboticsystem 110, and a handheld intelligent surgical instrument 112, whichare configured to communicate with one another and/or the hub 106. Insome aspects, a surgical system 102 may include an M number of hubs 106,an N number of visualization systems 108, an O number of robotic systems110, and a P number of handheld intelligent surgical instruments 112,where M, N, O, and P are integers greater than or equal to one.

FIG. 3 depicts an example of a surgical system 102 being used to performa surgical procedure on a patient who is lying down on an operatingtable 114 in a surgical operating room 116. A robotic system 110 is usedin the surgical procedure as a part of the surgical system 102. Therobotic system 110 includes a surgeon's console 118, a patient side cart120 (surgical robot), and a surgical robotic hub 122. The patient sidecart 120 can manipulate at least one removably coupled surgical tool 117through a minimally invasive incision in the body of the patient whilethe surgeon views the surgical site through the surgeon's console 118.An image of the surgical site can be obtained by a medical imagingdevice 124, which can be manipulated by the patient side cart 120 toorient the imaging device 124. The robotic hub 122 can be used toprocess the images of the surgical site for subsequent display to thesurgeon through the surgeon's console 118.

Other types of robotic systems can be readily adapted for use with thesurgical system 102. Various examples of robotic systems and surgicaltools that are suitable for use with the present disclosure aredescribed in U.S. Provisional Patent Application Ser. No. 62/611,339,titled ROBOT ASSISTED SURGICAL PLATFORM, filed Dec. 28, 2017, thedisclosure of which is herein incorporated by reference in its entirety.

Various examples of cloud-based analytics that are performed by thecloud 104, and are suitable for use with the present disclosure, aredescribed in U.S. Provisional Patent Application Ser. No. 62/611,340,titled CLOUD-BASED MEDICAL ANALYTICS, filed Dec. 28, 2017, thedisclosure of which is herein incorporated by reference in its entirety.

In various aspects, the imaging device 124 includes at least one imagesensor and one or more optical components. Suitable image sensorsinclude, but are not limited to, Charge-Coupled Device (CCD) sensors andComplementary Metal-Oxide Semiconductor (CMOS) sensors.

The optical components of the imaging device 124 may include one or moreillumination sources and/or one or more lenses. The one or moreillumination sources may be directed to illuminate portions of thesurgical field. The one or more image sensors may receive lightreflected or refracted from the surgical field, including lightreflected or refracted from tissue and/or surgical instruments.

The one or more illumination sources may be configured to radiateelectromagnetic energy in the visible spectrum as well as the invisiblespectrum. The visible spectrum, sometimes referred to as the opticalspectrum or luminous spectrum, is that portion of the electromagneticspectrum that is visible to (i.e., can be detected by) the human eye andmay be referred to as visible light or simply light. A typical human eyewill respond to wavelengths in air that are from about 380 nm to about750 nm.

The invisible spectrum (i.e., the non-luminous spectrum) is that portionof the electromagnetic spectrum that lies below and above the visiblespectrum (i.e., wavelengths below about 380 nm and above about 750 nm).The invisible spectrum is not detectable by the human eye. Wavelengthsgreater than about 750 nm are longer than the red visible spectrum, andthey become invisible infrared (IR), microwave, and radioelectromagnetic radiation. Wavelengths less than about 380 nm areshorter than the violet spectrum, and they become invisible ultraviolet,x-ray, and gamma ray electromagnetic radiation.

In various aspects, the imaging device 124 is configured for use in aminimally invasive procedure. Examples of imaging devices suitable foruse with the present disclosure include, but not limited to, anarthroscope, angioscope, bronchoscope, choledochoscope, colonoscope,cytoscope, duodenoscope, enteroscope, esophagogastro-duodenoscope(gastroscope), endoscope, laryngoscope, nasopharyngo-neproscope,sigmoidoscope, thoracoscope, and ureteroscope.

In one aspect, the imaging device employs multi-spectrum monitoring todiscriminate topography and underlying structures. A multi-spectralimage is one that captures image data within specific wavelength rangesacross the electromagnetic spectrum. The wavelengths may be separated byfilters or by the use of instruments that are sensitive to particularwavelengths, including light from frequencies beyond the visible lightrange, e.g., IR and ultraviolet. Spectral imaging can allow extractionof additional information the human eye fails to capture with itsreceptors for red, green, and blue. The use of multi-spectral imaging isdescribed in greater detail under the heading “Advanced ImagingAcquisition Module” in U.S. Provisional Patent Application Ser. No.62/611,341, titled INTERACTIVE SURGICAL PLATFORM, filed Dec. 28, 2017,the disclosure of which is herein incorporated by reference in itsentirety. Multi-spectrum monitoring can be a useful tool in relocating asurgical field after a surgical task is completed to perform one or moreof the previously described tests on the treated tissue.

It is axiomatic that strict sterilization of the operating room andsurgical equipment is required during any surgery. The strict hygieneand sterilization conditions required in a “surgical theater,” i.e., anoperating or treatment room, necessitate the highest possible sterilityof all medical devices and equipment. Part of that sterilization processis the need to sterilize anything that comes in contact with the patientor penetrates the sterile field, including the imaging device 124 andits attachments and components. It will be appreciated that the sterilefield may be considered a specified area, such as within a tray or on asterile towel, that is considered free of microorganisms, or the sterilefield may be considered an area, immediately around a patient, who hasbeen prepared for a surgical procedure. The sterile field may includethe scrubbed team members, who are properly attired, and all furnitureand fixtures in the area.

In various aspects, the visualization system 108 includes one or moreimaging sensors, one or more image-processing units, one or more storagearrays, and one or more displays that are strategically arranged withrespect to the sterile field, as illustrated in FIG. 2. In one aspect,the visualization system 108 includes an interface for HL7, PACS, andEMR. Various components of the visualization system 108 are describedunder the heading “Advanced Imaging Acquisition Module” in U.S.Provisional Patent Application Ser. No. 62/611,341, titled INTERACTIVESURGICAL PLATFORM, filed Dec. 28, 2017, the disclosure of which isherein incorporated by reference in its entirety.

As illustrated in FIG. 2, a primary display 119 is positioned in thesterile field to be visible to an operator at the operating table 114.In addition, a visualization tower 111 is positioned outside the sterilefield. The visualization tower 111 includes a first non-sterile display107 and a second non-sterile display 109, which face away from eachother. The visualization system 108, guided by the hub 106, isconfigured to utilize the displays 107, 109, and 119 to coordinateinformation flow to operators inside and outside the sterile field. Forexample, the hub 106 may cause the visualization system 108 to display asnapshot of a surgical site, as recorded by an imaging device 124, on anon-sterile display 107 or 109, while maintaining a live feed of thesurgical site on the primary display 119. The snapshot on thenon-sterile display 107 or 109 can permit a non-sterile operator toperform a diagnostic step relevant to the surgical procedure, forexample.

In one aspect, the hub 106 is also configured to route a diagnosticinput or feedback entered by a non-sterile operator at the visualizationtower 111 to the primary display 119 within the sterile field, where itcan be viewed by a sterile operator at the operating table. In oneexample, the input can be in the form of a modification to the snapshotdisplayed on the non-sterile display 107 or 109, which can be routed tothe primary display 119 by the hub 106.

Referring to FIG. 2, a surgical instrument 112 is being used in thesurgical procedure as part of the surgical system 102. The hub 106 isalso configured to coordinate information flow to a display of thesurgical instrument 112. For example, in U.S. Provisional PatentApplication Ser. No. 62/611,341, titled INTERACTIVE SURGICAL PLATFORM,filed Dec. 28, 2017, the disclosure of which is herein incorporated byreference in its entirety. A diagnostic input or feedback entered by anon-sterile operator at the visualization tower 111 can be routed by thehub 106 to the surgical instrument display 115 within the sterile field,where it can be viewed by the operator of the surgical instrument 112.Example surgical instruments that are suitable for use with the surgicalsystem 102 are described under the heading SURGICAL INSTRUMENT HARDWAREand in U.S. Provisional Patent Application Ser. No. 62/611,341, titledINTERACTIVE SURGICAL PLATFORM, filed Dec. 28, 2017, the disclosure ofwhich is herein incorporated by reference in its entirety, for example.

Referring now to FIG. 3, a hub 106 is depicted in communication with avisualization system 108, a robotic system 110, and a handheldintelligent surgical instrument 112. The hub 106 includes a hub display135, an imaging module 138, a generator module 140, a communicationmodule 130, a processor module 132, and a storage array 134. In certainaspects, as illustrated in FIG. 3, the hub 106 further includes a smokeevacuation module 126 and/or a suction/irrigation module 128.

During a surgical procedure, energy application to tissue, for sealingand/or cutting, is generally associated with smoke evacuation, suctionof excess fluid, and/or irrigation of the tissue. Fluid, power, and/ordata lines from different sources are often entangled during thesurgical procedure. Valuable time can be lost addressing this issueduring a surgical procedure. Detangling the lines may necessitatedisconnecting the lines from their respective modules, which may requireresetting the modules. The hub modular enclosure 136 offers a unifiedenvironment for managing the power, data, and fluid lines, which reducesthe frequency of entanglement between such lines.

Aspects of the present disclosure present a surgical hub for use in asurgical procedure that involves energy application to tissue at asurgical site. The surgical hub includes a hub enclosure and a combogenerator module slidably receivable in a docking station of the hubenclosure. The docking station includes data and power contacts. Thecombo generator module includes two or more of an ultrasonic energygenerator component, a bipolar RF energy generator component, and amonopolar RF energy generator component that are housed in a singleunit. In one aspect, the combo generator module also includes a smokeevacuation component, at least one energy delivery cable for connectingthe combo generator module to a surgical instrument, at least one smokeevacuation component configured to evacuate smoke, fluid, and/orparticulates generated by the application of therapeutic energy to thetissue, and a fluid line extending from the remote surgical site to thesmoke evacuation component.

In one aspect, the fluid line is a first fluid line and a second fluidline extends from the remote surgical site to a suction and irrigationmodule slidably received in the hub enclosure. In one aspect, the hubenclosure comprises a fluid interface.

Certain surgical procedures may require the application of more than oneenergy type to the tissue. One energy type may be more beneficial forcutting the tissue, while another different energy type may be morebeneficial for sealing the tissue. For example, a bipolar generator canbe used to seal the tissue while an ultrasonic generator can be used tocut the sealed tissue. Aspects of the present disclosure present asolution where a hub modular enclosure 136 is configured to accommodatedifferent generators, and facilitate an interactive communicationtherebetween. One of the advantages of the hub modular enclosure 136 isenabling the quick removal and/or replacement of various modules.

Aspects of the present disclosure present a modular surgical enclosurefor use in a surgical procedure that involves energy application totissue. The modular surgical enclosure includes a first energy-generatormodule, configured to generate a first energy for application to thetissue, and a first docking station comprising a first docking port thatincludes first data and power contacts, wherein the firstenergy-generator module is slidably movable into an electricalengagement with the power and data contacts and wherein the firstenergy-generator module is slidably movable out of the electricalengagement with the first power and data contacts,

Further to the above, the modular surgical enclosure also includes asecond energy-generator module configured to generate a second energy,different than the first energy, for application to the tissue, and asecond docking station comprising a second docking port that includessecond data and power contacts, wherein the second energy-generatormodule is slidably movable into an electrical engagement with the powerand data contacts, and wherein the second energy-generator module isslidably movable out of the electrical engagement with the second powerand data contacts.

In addition, the modular surgical enclosure also includes acommunication bus between the first docking port and the second dockingport, configured to facilitate communication between the firstenergy-generator module and the second energy-generator module.

Referring to FIGS. 3-7, aspects of the present disclosure are presentedfor a hub modular enclosure 136 that allows the modular integration of agenerator module 140, a smoke evacuation module 126, and asuction/irrigation module 128. The hub modular enclosure 136 furtherfacilitates interactive communication between the modules 140, 126, 128.As illustrated in FIG. 5, the generator module 140 can be a generatormodule with integrated monopolar, bipolar, and ultrasonic componentssupported in a single housing unit 139 slidably insertable into the hubmodular enclosure 136. As illustrated in FIG. 5, the generator module140 can be configured to connect to a monopolar device 146, a bipolardevice 147, and an ultrasonic device 148. Alternatively, the generatormodule 140 may comprise a series of monopolar, bipolar, and/orultrasonic generator modules that interact through the hub modularenclosure 136. The hub modular enclosure 136 can be configured tofacilitate the insertion of multiple generators and interactivecommunication between the generators docked into the hub modularenclosure 136 so that the generators would act as a single generator.

In one aspect, the hub modular enclosure 136 comprises a modular powerand communication backplane 149 with external and wireless communicationheaders to enable the removable attachment of the modules 140, 126, 128and interactive communication therebetween.

In one aspect, the hub modular enclosure 136 includes docking stations,or drawers, 151, herein also referred to as drawers, which areconfigured to slidably receive the modules 140, 126, 128. FIG. 4illustrates a partial perspective view of a surgical hub enclosure 136,and a combo generator module 145 slidably receivable in a dockingstation 151 of the surgical hub enclosure 136. A docking port 152 withpower and data contacts on a rear side of the combo generator module 145is configured to engage a corresponding docking port 150 with power anddata contacts of a corresponding docking station 151 of the hub modularenclosure 136 as the combo generator module 145 is slid into positionwithin the corresponding docking station 151 of the hub module enclosure136. In one aspect, the combo generator module 145 includes a bipolar,ultrasonic, and monopolar module and a smoke evacuation moduleintegrated together into a single housing unit 139, as illustrated inFIG. 5.

In various aspects, the smoke evacuation module 126 includes a fluidline 154 that conveys captured/collected smoke and/or fluid away from asurgical site and to, for example, the smoke evacuation module 126.Vacuum suction originating from the smoke evacuation module 126 can drawthe smoke into an opening of a utility conduit at the surgical site. Theutility conduit, coupled to the fluid line, can be in the form of aflexible tube terminating at the smoke evacuation module 126. Theutility conduit and the fluid line define a fluid path extending towardthe smoke evacuation module 126 that is received in the hub enclosure136.

In various aspects, the suction/irrigation module 128 is coupled to asurgical tool comprising an aspiration fluid line and a suction fluidline. In one example, the aspiration and suction fluid lines are in theform of flexible tubes extending from the surgical site toward thesuction/irrigation module 128. One or more drive systems can beconfigured to cause irrigation and aspiration of fluids to and from thesurgical site.

In one aspect, the surgical tool includes a shaft having an end effectorat a distal end thereof and at least one energy treatment associatedwith the end effector, an aspiration tube, and an irrigation tube. Theaspiration tube can have an inlet port at a distal end thereof and theaspiration tube extends through the shaft. Similarly, an irrigation tubecan extend through the shaft and can have an inlet port in proximity tothe energy deliver implement. The energy deliver implement is configuredto deliver ultrasonic and/or RF energy to the surgical site and iscoupled to the generator module 140 by a cable extending initiallythrough the shaft.

The irrigation tube can be in fluid communication with a fluid source,and the aspiration tube can be in fluid communication with a vacuumsource. The fluid source and/or the vacuum source can be housed in thesuction/irrigation module 128. In one example, the fluid source and/orthe vacuum source can be housed in the hub enclosure 136 separately fromthe suction/irrigation module 128. In such example, a fluid interfacecan be configured to connect the suction/irrigation module 128 to thefluid source and/or the vacuum source.

In one aspect, the modules 140, 126, 128 and/or their correspondingdocking stations on the hub modular enclosure 136 may include alignmentfeatures that are configured to align the docking ports of the modulesinto engagement with their counterparts in the docking stations of thehub modular enclosure 136. For example, as illustrated in FIG. 4, thecombo generator module 145 includes side brackets 155 that areconfigured to slidably engage with corresponding brackets 156 of thecorresponding docking station 151 of the hub modular enclosure 136. Thebrackets cooperate to guide the docking port contacts of the combogenerator module 145 into an electrical engagement with the docking portcontacts of the hub modular enclosure 136.

In some aspects, the drawers 151 of the hub modular enclosure 136 arethe same, or substantially the same size, and the modules are adjustedin size to be received in the drawers 151. For example, the sidebrackets 155 and/or 156 can be larger or smaller depending on the sizeof the module. In other aspects, the drawers 151 are different in sizeand are each designed to accommodate a particular module.

Furthermore, the contacts of a particular module can be keyed forengagement with the contacts of a particular drawer to avoid inserting amodule into a drawer with mismatching contacts.

As illustrated in FIG. 4, the docking port 150 of one drawer 151 can becoupled to the docking port 150 of another drawer 151 through acommunications link 157 to facilitate an interactive communicationbetween the modules housed in the hub modular enclosure 136. The dockingports 150 of the hub modular enclosure 136 may alternatively, oradditionally, facilitate a wireless interactive communication betweenthe modules housed in the hub modular enclosure 136. Any suitablewireless communication can be employed, such as for example AirTitan-Bluetooth.

FIG. 6 illustrates individual power bus attachments for a plurality oflateral docking ports of a lateral modular housing 160 configured toreceive a plurality of modules of a surgical hub 206. The lateralmodular housing 160 is configured to laterally receive and interconnectthe modules 161. The modules 161 are slidably inserted into dockingstations 162 of lateral modular housing 160, which includes a backplanefor interconnecting the modules 161. As illustrated in FIG. 6, themodules 161 are arranged laterally in the lateral modular housing 160.Alternatively, the modules 161 may be arranged vertically in a lateralmodular housing.

FIG. 7 illustrates a vertical modular housing 164 configured to receivea plurality of modules 165 of the surgical hub 106. The modules 165 areslidably inserted into docking stations, or drawers, 167 of verticalmodular housing 164, which includes a backplane for interconnecting themodules 165. Although the drawers 167 of the vertical modular housing164 are arranged vertically, in certain instances, a vertical modularhousing 164 may include drawers that are arranged laterally.Furthermore, the modules 165 may interact with one another through thedocking ports of the vertical modular housing 164. In the example ofFIG. 7, a display 177 is provided for displaying data relevant to theoperation of the modules 165. In addition, the vertical modular housing164 includes a master module 178 housing a plurality of sub-modules thatare slidably received in the master module 178.

In various aspects, the imaging module 138 comprises an integrated videoprocessor and a modular light source and is adapted for use with variousimaging devices. In one aspect, the imaging device is comprised of amodular housing that can be assembled with a light source module and acamera module. The housing can be a disposable housing. In at least oneexample, the disposable housing is removably coupled to a reusablecontroller, a light source module, and a camera module. The light sourcemodule and/or the camera module can be selectively chosen depending onthe type of surgical procedure. In one aspect, the camera modulecomprises a CCD sensor. In another aspect, the camera module comprises aCMOS sensor. In another aspect, the camera module is configured forscanned beam imaging. Likewise, the light source module can beconfigured to deliver a white light or a different light, depending onthe surgical procedure.

During a surgical procedure, removing a surgical device from thesurgical field and replacing it with another surgical device thatincludes a different camera or a different light source can beinefficient. Temporarily losing sight of the surgical field may lead toundesirable consequences. The module imaging device of the presentdisclosure is configured to permit the replacement of a light sourcemodule or a camera module midstream during a surgical procedure, withouthaving to remove the imaging device from the surgical field.

In one aspect, the imaging device comprises a tubular housing thatincludes a plurality of channels. A first channel is configured toslidably receive the camera module, which can be configured for asnap-fit engagement with the first channel. A second channel isconfigured to slidably receive the light source module, which can beconfigured for a snap-fit engagement with the second channel. In anotherexample, the camera module and/or the light source module can be rotatedinto a final position within their respective channels. A threadedengagement can be employed in lieu of the snap-fit engagement.

In various examples, multiple imaging devices are placed at differentpositions in the surgical field to provide multiple views. The imagingmodule 138 can be configured to switch between the imaging devices toprovide an optimal view. In various aspects, the imaging module 138 canbe configured to integrate the images from the different imaging device.

Various image processors and imaging devices suitable for use with thepresent disclosure are described in U.S. Pat. No. 7,995,045, titledCOMBINED SBI AND CONVENTIONAL IMAGE PROCESSOR, which issued on Aug. 9,2011, which is herein incorporated by reference in its entirety. Inaddition, U.S. Pat. No. 7,982,776, titled SBI MOTION ARTIFACT REMOVALAPPARATUS AND METHOD, which issued on Jul. 19, 2011, which is hereinincorporated by reference in its entirety, describes various systems forremoving motion artifacts from image data. Such systems can beintegrated with the imaging module 138. Furthermore, U.S. PatentApplication Publication No. 2011/0306840, titled CONTROLLABLE MAGNETICSOURCE TO FIXTURE INTRACORPOREAL APPARATUS, which published on Dec. 15,2011, and U.S. Patent Application Publication No. 2014/0243597, titledSYSTEM FOR PERFORMING A MINIMALLY INVASIVE SURGICAL PROCEDURE, whichpublished on Aug. 28, 2014, each of which is herein incorporated byreference in its entirety.

FIG. 8 illustrates a surgical data network 201 comprising a modularcommunication hub 203 configured to connect modular devices located inone or more operating theaters of a healthcare facility, or any room ina healthcare facility specially equipped for surgical operations, to acloud-based system (e.g., the cloud 204 that may include a remote server213 coupled to a storage device 205). In one aspect, the modularcommunication hub 203 comprises a network hub 207 and/or a networkswitch 209 in communication with a network router. The modularcommunication hub 203 also can be coupled to a local computer system 210to provide local computer processing and data manipulation. The surgicaldata network 201 may be configured as passive, intelligent, orswitching. A passive surgical data network serves as a conduit for thedata, enabling it to go from one device (or segment) to another and tothe cloud computing resources. An intelligent surgical data networkincludes additional features to enable the traffic passing through thesurgical data network to be monitored and to configure each port in thenetwork hub 207 or network switch 209. An intelligent surgical datanetwork may be referred to as a manageable hub or switch. A switchinghub reads the destination address of each packet and then forwards thepacket to the correct port.

Modular devices la-1n located in the operating theater may be coupled tothe modular communication hub 203. The network hub 207 and/or thenetwork switch 209 may be coupled to a network router 211 to connect thedevices 1 a-1 n to the cloud 204 or the local computer system 210. Dataassociated with the devices 1 a-1 n may be transferred to cloud-basedcomputers via the router for remote data processing and manipulation.Data associated with the devices 1 a-1 n may also be transferred to thelocal computer system 210 for local data processing and manipulation.Modular devices 2 a-2 m located in the same operating theater also maybe coupled to a network switch 209. The network switch 209 may becoupled to the network hub 207 and/or the network router 211 to connectto the devices 2 a-2 m to the cloud 204. Data associated with thedevices 2 a-2 n may be transferred to the cloud 204 via the networkrouter 211 for data processing and manipulation. Data associated withthe devices 2 a-2 m may also be transferred to the local computer system210 for local data processing and manipulation.

It will be appreciated that the surgical data network 201 may beexpanded by interconnecting multiple network hubs 207 and/or multiplenetwork switches 209 with multiple network routers 211. The modularcommunication hub 203 may be contained in a modular control towerconfigured to receive multiple devices 1 a-1 n/ 2 a-2 m. The localcomputer system 210 also may be contained in a modular control tower.The modular communication hub 203 is connected to a display 212 todisplay images obtained by some of the devices 1 a-1 n/ 2 a-2 m, forexample during surgical procedures. In various aspects, the devices 1a-1 n/ 2 a-2 m may include, for example, various modules such as animaging module 138 coupled to an endoscope, a generator module 140coupled to an energy-based surgical device, a smoke evacuation module126, a suction/irrigation module 128, a communication module 130, aprocessor module 132, a storage array 134, a surgical device coupled toa display, and/or a non-contact sensor module, among other modulardevices that may be connected to the modular communication hub 203 ofthe surgical data network 201.

In one aspect, the surgical data network 201 may comprise a combinationof network hub(s), network switch(es), and network router(s) connectingthe devices 1 a-1 n/ 2 a-2 m to the cloud. Any one of or all of thedevices 1 a-1 n/ 2 a-2 m coupled to the network hub or network switchmay collect data in real time and transfer the data to cloud computersfor data processing and manipulation. It will be appreciated that cloudcomputing relies on sharing computing resources rather than having localservers or personal devices to handle software applications. The word“cloud” may be used as a metaphor for “the Internet,” although the termis not limited as such. Accordingly, the term “cloud computing” may beused herein to refer to “a type of Internet-based computing,” wheredifferent services—such as servers, storage, and applications—aredelivered to the modular communication hub 203 and/or computer system210 located in the surgical theater (e.g., a fixed, mobile, temporary,or field operating room or space) and to devices connected to themodular communication hub 203 and/or computer system 210 through theInternet. The cloud infrastructure may be maintained by a cloud serviceprovider. In this context, the cloud service provider may be the entitythat coordinates the usage and control of the devices 1 a-1 n/ 2 a-2 mlocated in one or more operating theaters. The cloud computing servicescan perform a large number of calculations based on the data gathered bysmart surgical instruments, robots, and other computerized deviceslocated in the operating theater. The hub hardware enables multipledevices or connections to be connected to a computer that communicateswith the cloud computing resources and storage.

Applying cloud computer data processing techniques on the data collectedby the devices 1 a-1 n/ 2 a-2 m, the surgical data network providesimproved surgical outcomes, reduced costs, and improved patientsatisfaction. At least some of the devices 1 a-1 n/ 2 a-2 m may beemployed to view tissue states to assess leaks or perfusion of sealedtissue after a tissue sealing and cutting procedure. At least some ofthe devices 1 a-1 n/ 2 a-2 m may be employed to identify pathology, suchas the effects of diseases, using the cloud-based computing to examinedata including images of samples of body tissue for diagnostic purposes.This includes localization and margin confirmation of tissue andphenotypes. At least some of the devices 1 a-1 n/ 2 a-2 m may beemployed to identify anatomical structures of the body using a varietyof sensors integrated with imaging devices and techniques such asoverlaying images captured by multiple imaging devices. The datagathered by the devices 1 a-1 n/ 2 a-2 m, including image data, may betransferred to the cloud 204 or the local computer system 210 or bothfor data processing and manipulation including image processing andmanipulation. The data may be analyzed to improve surgical procedureoutcomes by determining if further treatment, such as the application ofendoscopic intervention, emerging technologies, a targeted radiation,targeted intervention, and precise robotics to tissue-specific sites andconditions, may be pursued. Such data analysis may further employoutcome analytics processing, and using standardized approaches mayprovide beneficial feedback to either confirm surgical treatments andthe behavior of the surgeon or suggest modifications to surgicaltreatments and the behavior of the surgeon.

In one implementation, the operating theater devices 1 a-1 n may beconnected to the modular communication hub 203 over a wired channel or awireless channel depending on the configuration of the devices 1 a-1 nto a network hub. The network hub 207 may be implemented, in one aspect,as a local network broadcast device that works on the physical layer ofthe Open System Interconnection (OSI) model. The network hub providesconnectivity to the devices 1 a-1 n located in the same operatingtheater network. The network hub 207 collects data in the form ofpackets and sends them to the router in half duplex mode. The networkhub 207 does not store any media access control/Internet Protocol(MAC/IP) to transfer the device data. Only one of the devices 1 a-1 ncan send data at a time through the network hub 207. The network hub 207has no routing tables or intelligence regarding where to sendinformation and broadcasts all network data across each connection andto a remote server 213 (FIG. 9) over the cloud 204. The network hub 207can detect basic network errors such as collisions, but having allinformation broadcast to multiple ports can be a security risk and causebottlenecks.

In another implementation, the operating theater devices 2 a-2 m may beconnected to a network switch 209 over a wired channel or a wirelesschannel. The network switch 209 works in the data link layer of the OSImodel. The network switch 209 is a multicast device for connecting thedevices 2 a-2 m located in the same operating theater to the network.The network switch 209 sends data in the form of frames to the networkrouter 211 and works in full duplex mode. Multiple devices 2 a-2 m cansend data at the same time through the network switch 209. The networkswitch 209 stores and uses MAC addresses of the devices 2 a-2 m totransfer data.

The network hub 207 and/or the network switch 209 are coupled to thenetwork router 211 for connection to the cloud 204. The network router211 works in the network layer of the OSI model. The network router 211creates a route for transmitting data packets received from the networkhub 207 and/or network switch 211 to cloud-based computer resources forfurther processing and manipulation of the data collected by any one ofor all the devices 1 a-1 n/ 2 a-2 m. The network router 211 may beemployed to connect two or more different networks located in differentlocations, such as, for example, different operating theaters of thesame healthcare facility or different networks located in differentoperating theaters of different healthcare facilities. The networkrouter 211 sends data in the form of packets to the cloud 204 and worksin full duplex mode. Multiple devices can send data at the same time.The network router 211 uses IP addresses to transfer data.

In one example, the network hub 207 may be implemented as a USB hub,which allows multiple USB devices to be connected to a host computer.The USB hub may expand a single USB port into several tiers so thatthere are more ports available to connect devices to the host systemcomputer. The network hub 207 may include wired or wireless capabilitiesto receive information over a wired channel or a wireless channel. Inone aspect, a wireless USB short-range, high-bandwidth wireless radiocommunication protocol may be employed for communication between thedevices 1 a-1 n and devices 2 a-2 m located in the operating theater.

In other examples, the operating theater devices 1 a-1 n/ 2 a-2 m maycommunicate to the modular communication hub 203 via Bluetooth wirelesstechnology standard for exchanging data over short distances (usingshort-wavelength UHF radio waves in the ISM band from 2.4 to 2.485 GHz)from fixed and mobile devices and building personal area networks(PANs). In other aspects, the operating theater devices 1 a-1 n/ 2 a-2 mmay communicate to the modular communication hub 203 via a number ofwireless or wired communication standards or protocols, including butnot limited to W-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16 family),IEEE 802.20, long-term evolution (LTE), and Ev-DO, HSPA+, HSDPA+,HSUPA+, EDGE, GSM, GPRS, CDMA, TDMA, DECT, and Ethernet derivativesthereof, as well as any other wireless and wired protocols that aredesignated as 3G, 4G, 5G, and beyond. The computing module may include aplurality of communication modules. For instance, a first communicationmodule may be dedicated to shorter-range wireless communications such asWi-Fi and Bluetooth, and a second communication module may be dedicatedto longer-range wireless communications such as GPS, EDGE, GPRS, CDMA,WiMAX, LTE, Ev-DO, and others.

The modular communication hub 203 may serve as a central connection forone or all of the operating theater devices 1 a-1 n/ 2 a-2 m and handlesa data type known as frames. Frames carry the data generated by thedevices 1 a-1 n/ 2 a-2 m. When a frame is received by the modularcommunication hub 203, it is amplified and transmitted to the networkrouter 211, which transfers the data to the cloud computing resources byusing a number of wireless or wired communication standards orprotocols, as described herein.

The modular communication hub 203 can be used as a standalone device orbe connected to compatible network hubs and network switches to form alarger network. The modular communication hub 203 is generally easy toinstall, configure, and maintain, making it a good option for networkingthe operating theater devices 1 a-1 n/ 2 a-2 m.

FIG. 9 illustrates a computer-implemented interactive surgical system200. The computer-implemented interactive surgical system 200 is similarin many respects to the computer-implemented interactive surgical system100. For example, the computer-implemented interactive surgical system200 includes one or more surgical systems 202, which are similar in manyrespects to the surgical systems 102. Each surgical system 202 includesat least one surgical hub 206 in communication with a cloud 204 that mayinclude a remote server 213. In one aspect, the computer-implementedinteractive surgical system 200 comprises a modular control tower 236connected to multiple operating theater devices such as, for example,intelligent surgical instruments, robots, and other computerized deviceslocated in the operating theater. As shown in FIG. 10, the modularcontrol tower 236 comprises a modular communication hub 203 coupled to acomputer system 210. As illustrated in the example of FIG. 9, themodular control tower 236 is coupled to an imaging module 238 that iscoupled to an endoscope 239, a generator module 240 that is coupled toan energy device 241, a smoke evacuator module 226, a suction/irrigationmodule 228, a communication module 230, a processor module 232, astorage array 234, a smart device/instrument 235 optionally coupled to adisplay 237, and a non-contact sensor module 242. The operating theaterdevices are coupled to cloud computing resources and data storage viathe modular control tower 236. A robot hub 222 also may be connected tothe modular control tower 236 and to the cloud computing resources. Thedevices/instruments 235, visualization systems 208, among others, may becoupled to the modular control tower 236 via wired or wirelesscommunication standards or protocols, as described herein. The modularcontrol tower 236 may be coupled to a hub display 215 (e.g., monitor,screen) to display and overlay images received from the imaging module,device/instrument display, and/or other visualization systems 208. Thehub display also may display data received from devices connected to themodular control tower in conjunction with images and overlaid images.

FIG. 10 illustrates a surgical hub 206 comprising a plurality of modulescoupled to the modular control tower 236. The modular control tower 236comprises a modular communication hub 203, e.g., a network connectivitydevice, and a computer system 210 to provide local processing,visualization, and imaging, for example. As shown in FIG. 10, themodular communication hub 203 may be connected in a tiered configurationto expand the number of modules (e.g., devices) that may be connected tothe modular communication hub 203 and transfer data associated with themodules to the computer system 210, cloud computing resources, or both.As shown in FIG. 10, each of the network hubs/switches in the modularcommunication hub 203 includes three downstream ports and one upstreamport. The upstream network hub/switch is connected to a processor toprovide a communication connection to the cloud computing resources anda local display 217. Communication to the cloud 204 may be made eitherthrough a wired or a wireless communication channel.

The surgical hub 206 employs a non-contact sensor module 242 to measurethe dimensions of the operating theater and generate a map of thesurgical theater using either ultrasonic or laser-type non-contactmeasurement devices. An ultrasound-based non-contact sensor module scansthe operating theater by transmitting a burst of ultrasound andreceiving the echo when it bounces off the perimeter walls of anoperating theater as described under the heading “Surgical Hub SpatialAwareness Within an Operating Room” in U.S. Provisional PatentApplication Ser. No. 62/611,341, titled INTERACTIVE SURGICAL PLATFORM,filed Dec. 28, 2017, which is herein incorporated by reference in itsentirety, in which the sensor module is configured to determine the sizeof the operating theater and to adjust Bluetooth-pairing distancelimits. A laser-based non-contact sensor module scans the operatingtheater by transmitting laser light pulses, receiving laser light pulsesthat bounce off the perimeter walls of the operating theater, andcomparing the phase of the transmitted pulse to the received pulse todetermine the size of the operating theater and to adjust Bluetoothpairing distance limits, for example.

The computer system 210 comprises a processor 244 and a networkinterface 245. The processor 244 is coupled to a communication module247, storage 248, memory 249, non-volatile memory 250, and input/outputinterface 251 via a system bus. The system bus can be any of severaltypes of bus structure(s) including the memory bus or memory controller,a peripheral bus or external bus, and/or a local bus using any varietyof available bus architectures including, but not limited to, 9-bit bus,Industrial Standard Architecture (ISA), Micro-Charmel Architecture(MSA), Extended ISA (EISA), Intelligent Drive Electronics (IDE), VESALocal Bus (VLB), Peripheral Component Interconnect (PCI), USB, AdvancedGraphics Port (AGP), Personal Computer Memory Card InternationalAssociation bus (PCMCIA), Small Computer Systems Interface (SCSI), orany other proprietary bus.

The processor 244 may be any single-core or multicore processor such asthose known under the trade name ARM Cortex by Texas Instruments. In oneaspect, the processor may be an LM4F230H5QR ARM Cortex-M4F ProcessorCore, available from Texas Instruments, for example, comprising anon-chip memory of 256 KB single-cycle flash memory, or othernon-volatile memory, up to 40 MHz, a prefetch buffer to improveperformance above 40 MHz, a 32 KB single-cycle serial random accessmemory (SRAM), an internal read-only memory (ROM) loaded withStellarisWare® software, a 2 KB electrically erasable programmableread-only memory (EEPROM), and/or one or more pulse width modulation(PWM) modules, one or more quadrature encoder inputs (QEI) analogs, oneor more 12-bit analog-to-digital converters (ADCs) with 12 analog inputchannels, details of which are available for the product datasheet.

In one aspect, the processor 244 may comprise a safety controllercomprising two controller-based families such as TMS570 and RM4x, knownunder the trade name Hercules ARM Cortex R4, also by Texas Instruments.The safety controller may be configured specifically for IEC 61508 andISO 26262 safety critical applications, among others, to provideadvanced integrated safety features while delivering scalableperformance, connectivity, and memory options.

The system memory includes volatile memory and non-volatile memory. Thebasic input/output system (BIOS), containing the basic routines totransfer information between elements within the computer system, suchas during start-up, is stored in non-volatile memory. For example, thenon-volatile memory can include ROM, programmable ROM (PROM),electrically programmable ROM (EPROM), EEPROM, or flash memory. Volatilememory includes random-access memory (RAM), which acts as external cachememory. Moreover, RAM is available in many forms such as SRAM, dynamicRAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and directRambus RAM (DRRAM).

The computer system 210 also includes removable/non-removable,volatile/non-volatile computer storage media, such as for example diskstorage. The disk storage includes, but is not limited to, devices likea magnetic disk drive, floppy disk drive, tape drive, Jaz drive, Zipdrive, LS-60 drive, flash memory card, or memory stick. In addition, thedisk storage can include storage media separately or in combination withother storage media including, but not limited to, an optical disc drivesuch as a compact disc ROM device (CD-ROM), compact disc recordabledrive (CD-R Drive), compact disc rewritable drive (CD-RW Drive), or adigital versatile disc ROM drive (DVD-ROM). To facilitate the connectionof the disk storage devices to the system bus, a removable ornon-removable interface may be employed.

It is to be appreciated that the computer system 210 includes softwarethat acts as an intermediary between users and the basic computerresources described in a suitable operating environment. Such softwareincludes an operating system. The operating system, which can be storedon the disk storage, acts to control and allocate resources of thecomputer system. System applications take advantage of the management ofresources by the operating system through program modules and programdata stored either in the system memory or on the disk storage. It is tobe appreciated that various components described herein can beimplemented with various operating systems or combinations of operatingsystems.

A user enters commands or information into the computer system 210through input device(s) coupled to the I/O interface 251. The inputdevices include, but are not limited to, a pointing device such as amouse, trackball, stylus, touch pad, keyboard, microphone, joystick,game pad, satellite dish, scanner, TV tuner card, digital camera,digital video camera, web camera, and the like. These and other inputdevices connect to the processor through the system bus via interfaceport(s). The interface port(s) include, for example, a serial port, aparallel port, a game port, and a USB. The output device(s) use some ofthe same types of ports as input device(s). Thus, for example, a USBport may be used to provide input to the computer system and to outputinformation from the computer system to an output device. An outputadapter is provided to illustrate that there are some output deviceslike monitors, displays, speakers, and printers, among other outputdevices that require special adapters. The output adapters include, byway of illustration and not limitation, video and sound cards thatprovide a means of connection between the output device and the systembus. It should be noted that other devices and/or systems of devices,such as remote computer(s), provide both input and output capabilities.

The computer system 210 can operate in a networked environment usinglogical connections to one or more remote computers, such as cloudcomputer(s), or local computers. The remote cloud computer(s) can be apersonal computer, server, router, network PC, workstation,microprocessor-based appliance, peer device, or other common networknode, and the like, and typically includes many or all of the elementsdescribed relative to the computer system. For purposes of brevity, onlya memory storage device is illustrated with the remote computer(s). Theremote computer(s) is logically connected to the computer system througha network interface and then physically connected via a communicationconnection. The network interface encompasses communication networkssuch as local area networks (LANs) and wide area networks (WANs). LANtechnologies include Fiber Distributed Data Interface (FDDI), CopperDistributed Data Interface (CDDI), Ethernet/IEEE 802.3, Token Ring/IEEE802.5 and the like. WAN technologies include, but are not limited to,point-to-point links, circuit-switching networks like IntegratedServices Digital Networks (ISDN) and variations thereon,packet-switching networks, and Digital Subscriber Lines (DSL).

In various aspects, the computer system 210 of FIG. 10, the imagingmodule 238 and/or visualization system 208, and/or the processor module232 of FIGS. 9-10, may comprise an image processor, image-processingengine, media processor, or any specialized digital signal processor(DSP) used for the processing of digital images. The image processor mayemploy parallel computing with single instruction, multiple data (SIMD)or multiple instruction, multiple data (MIMD) technologies to increasespeed and efficiency. The digital image-processing engine can perform arange of tasks. The image processor may be a system on a chip withmulticore processor architecture.

The communication connection(s) refers to the hardware/software employedto connect the network interface to the bus. While the communicationconnection is shown for illustrative clarity inside the computer system,it can also be external to the computer system 210. Thehardware/software necessary for connection to the network interfaceincludes, for illustrative purposes only, internal and externaltechnologies such as modems, including regular telephone-grade modems,cable modems, and DSL modems, ISDN adapters, and Ethernet cards.

FIG. 11 illustrates a functional block diagram of one aspect of a USBnetwork hub 300 device, in accordance with at least one aspect of thepresent disclosure. In the illustrated aspect, the USB network hubdevice 300 employs a TUSB2036 integrated circuit hub by TexasInstruments. The USB network hub 300 is a CMOS device that provides anupstream USB transceiver port 302 and up to three downstream USBtransceiver ports 304, 306, 308 in compliance with the USB 2.0specification. The upstream USB transceiver port 302 is a differentialroot data port comprising a differential data minus (DMO) input pairedwith a differential data plus (DPO) input. The three downstream USBtransceiver ports 304, 306, 308 are differential data ports where eachport includes differential data plus (DP1-DP3) outputs paired withdifferential data minus (DM1-DM3) outputs.

The USB network hub 300 device is implemented with a digital statemachine instead of a microcontroller, and no firmware programming isrequired. Fully compliant USB transceivers are integrated into thecircuit for the upstream USB transceiver port 302 and all downstream USBtransceiver ports 304, 306, 308. The downstream USB transceiver ports304, 306, 308 support both full-speed and low-speed devices byautomatically setting the slew rate according to the speed of the deviceattached to the ports. The USB network hub 300 device may be configuredeither in bus-powered or self-powered mode and includes a hub powerlogic 312 to manage power.

The USB network hub 300 device includes a serial interface engine 310(SIE). The SIE 310 is the front end of the USB network hub 300 hardwareand handles most of the protocol described in chapter 8 of the USBspecification. The SIE 310 typically comprehends signaling up to thetransaction level. The functions that it handles could include: packetrecognition, transaction sequencing, SOP, EOP, RESET, and RESUME signaldetection/generation, clock/data separation, non-return-to-zero invert(NRZI) data encoding/decoding and bit-stuffing, CRC generation andchecking (token and data), packet ID (PID) generation andchecking/decoding, and/or serial-parallel/parallel-serial conversion.The 310 receives a clock input 314 and is coupled to a suspend/resumelogic and frame timer 316 circuit and a hub repeater circuit 318 tocontrol communication between the upstream USB transceiver port 302 andthe downstream USB transceiver ports 304, 306, 308 through port logiccircuits 320, 322, 324. The SIE 310 is coupled to a command decoder 326via interface logic to control commands from a serial EEPROM via aserial EEPROM interface 330.

In various aspects, the USB network hub 300 can connect 127 functionsconfigured in up to six logical layers (tiers) to a single computer.Further, the USB network hub 300 can connect to all peripherals using astandardized four-wire cable that provides both communication and powerdistribution. The power configurations are bus-powered and self-poweredmodes. The USB network hub 300 may be configured to support four modesof power management: a bus-powered hub, with either individual-portpower management or ganged-port power management, and the self-poweredhub, with either individual-port power management or ganged-port powermanagement. In one aspect, using a USB cable, the USB network hub 300,the upstream USB transceiver port 302 is plugged into a USB hostcontroller, and the downstream USB transceiver ports 304, 306, 308 areexposed for connecting USB compatible devices, and so forth.

Surgical Instrument Hardware

FIG. 12 illustrates a logic diagram of a control system 470 of asurgical instrument or tool in accordance with one or more aspects ofthe present disclosure. The system 470 comprises a control circuit. Thecontrol circuit includes a microcontroller 461 comprising a processor462 and a memory 468. One or more of sensors 472, 474, 476, for example,provide real-time feedback to the processor 462. A motor 482, driven bya motor driver 492, operably couples a longitudinally movabledisplacement member to drive a clamp arm closure member. A trackingsystem 480 is configured to determine the position of the longitudinallymovable displacement member. The position information is provided to theprocessor 462, which can be programmed or configured to determine theposition of the longitudinally movable drive member as well as theposition of the closure member. Additional motors may be provided at thetool driver interface to control closure tube travel, shaft rotation,articulation, or clamp arm closure, or a combination of the above. Adisplay 473 displays a variety of operating conditions of theinstruments and may include touch screen functionality for data input.Information displayed on the display 473 may be overlaid with imagesacquired via endoscopic imaging modules.

In one aspect, the microcontroller 461 may be any single-core ormulticore processor such as those known under the trade name ARM Cortexby Texas Instruments. In one aspect, the main microcontroller 461 may bean LM4F230H5QR ARM Cortex-M4F Processor Core, available from TexasInstruments, for example, comprising an on-chip memory of 256 KBsingle-cycle flash memory, or other non-volatile memory, up to 40 MHz, aprefetch buffer to improve performance above 40 MHz, a 32 KBsingle-cycle SRAM, and internal ROM loaded with StellarisWare® software,a 2 KB EEPROM, one or more PWM modules, one or more QEI analogs, and/orone or more 12-bit ADCs with 12 analog input channels, details of whichare available for the product datasheet.

In one aspect, the microcontroller 461 may comprise a safety controllercomprising two controller-based families such as TMS570 and RM4x, knownunder the trade name Hercules ARM Cortex R4, also by Texas Instruments.The safety controller may be configured specifically for IEC 61508 andISO 26262 safety critical applications, among others, to provideadvanced integrated safety features while delivering scalableperformance, connectivity, and memory options.

The microcontroller 461 may be programmed to perform various functionssuch as precise control over the speed and position of the knife,articulation systems, clamp arm, or a combination of the above. In oneaspect, the microcontroller 461 includes a processor 462 and a memory468. The electric motor 482 may be a brushed direct current (DC) motorwith a gearbox and mechanical links to an articulation or knife system.In one aspect, a motor driver 492 may be an A3941 available from AllegroMicrosystems, Inc. Other motor drivers may be readily substituted foruse in the tracking system 480 comprising an absolute positioningsystem. A detailed description of an absolute positioning system isdescribed in U.S. Patent Application Publication No. 2017/0296213,titled SYSTEMS AND METHODS FOR CONTROLLING A SURGICAL STAPLING ANDCUTTING INSTRUMENT, which published on Oct. 19, 2017, which is hereinincorporated by reference in its entirety.

The microcontroller 461 may be programmed to provide precise controlover the speed and position of displacement members and articulationsystems. The microcontroller 461 may be configured to compute a responsein the software of the microcontroller 461. The computed response iscompared to a measured response of the actual system to obtain an“observed” response, which is used for actual feedback decisions. Theobserved response is a favorable, tuned value that balances the smooth,continuous nature of the simulated response with the measured response,which can detect outside influences on the system.

In one aspect, the motor 482 may be controlled by the motor driver 492and can be employed by the firing system of the surgical instrument ortool. In various forms, the motor 482 may be a brushed DC driving motorhaving a maximum rotational speed of approximately 25,000 RPM. In otherarrangements, the motor 482 may include a brushless motor, a cordlessmotor, a synchronous motor, a stepper motor, or any other suitableelectric motor. The motor driver 492 may comprise an H-bridge drivercomprising field-effect transistors (FETs), for example. The motor 482can be powered by a power assembly releasably mounted to the handleassembly or tool housing for supplying control power to the surgicalinstrument or tool. The power assembly may comprise a battery which mayinclude a number of battery cells connected in series that can be usedas the power source to power the surgical instrument or tool. In certaincircumstances, the battery cells of the power assembly may bereplaceable and/or rechargeable battery cells. In at least one example,the battery cells can be lithium-ion batteries which can be couplable toand separable from the power assembly.

The motor driver 492 may be an A3941 available from AllegroMicrosystems, Inc. The A3941 492 is a full-bridge controller for usewith external N-channel power metal-oxide semiconductor field-effecttransistors (MOSFETs) specifically designed for inductive loads, such asbrush DC motors. The driver 492 comprises a unique charge pump regulatorthat provides full (>10 V) gate drive for battery voltages down to 7 Vand allows the A3941 to operate with a reduced gate drive, down to 5.5V. A bootstrap capacitor may be employed to provide the above batterysupply voltage required for N-channel MOSFETs. An internal charge pumpfor the high-side drive allows DC (100% duty cycle) operation. The fullbridge can be driven in fast or slow decay modes using diode orsynchronous rectification. In the slow decay mode, current recirculationcan be through the high-side or the low-side FETs. The power FETs areprotected from shoot-through by resistor-adjustable dead time.Integrated diagnostics provide indications of undervoltage,overtemperature, and power bridge faults and can be configured toprotect the power MOSFETs under most short circuit conditions. Othermotor drivers may be readily substituted for use in the tracking system480 comprising an absolute positioning system.

The tracking system 480 comprises a controlled motor drive circuitarrangement comprising a position sensor 472 according to one aspect ofthis disclosure. The position sensor 472 for an absolute positioningsystem provides a unique position signal corresponding to the locationof a displacement member. In one aspect, the displacement memberrepresents a longitudinally movable drive member comprising a rack ofdrive teeth for meshing engagement with a corresponding drive gear of agear reducer assembly. In other aspects, the displacement memberrepresents the firing member, which could be adapted and configured toinclude a rack of drive teeth. In yet another aspect, the displacementmember represents a longitudinal displacement member to open and close aclamp arm, which can be adapted and configured to include a rack ofdrive teeth. In other aspects, the displacement member represents aclamp arm closure member configured to close and to open a clamp arm ofa stapler, ultrasonic, or electrosurgical device, or combinations of theabove. Accordingly, as used herein, the term displacement member is usedgenerically to refer to any movable member of the surgical instrument ortool such as the drive member, the clamp arm, or any element that can bedisplaced. Accordingly, the absolute positioning system can, in effect,track the displacement of the clamp arm by tracking the lineardisplacement of the longitudinally movable drive member.

In other aspects, the absolute positioning system can be configured totrack the position of a clamp arm in the process of closing or opening.In various other aspects, the displacement member may be coupled to anyposition sensor 472 suitable for measuring linear displacement. Thus,the longitudinally movable drive member, or clamp arm, or combinationsthereof, may be coupled to any suitable linear displacement sensor.Linear displacement sensors may include contact or non-contactdisplacement sensors. Linear displacement sensors may comprise linearvariable differential transformers (LVDT), differential variablereluctance transducers (DVRT), a slide potentiometer, a magnetic sensingsystem comprising a movable magnet and a series of linearly arrangedHall effect sensors, a magnetic sensing system comprising a fixed magnetand a series of movable, linearly arranged Hall effect sensors, anoptical sensing system comprising a movable light source and a series oflinearly arranged photo diodes or photo detectors, an optical sensingsystem comprising a fixed light source and a series of movable linearly,arranged photo diodes or photo detectors, or any combination thereof.

The electric motor 482 can include a rotatable shaft that operablyinterfaces with a gear assembly that is mounted in meshing engagementwith a set, or rack, of drive teeth on the displacement member. A sensorelement may be operably coupled to a gear assembly such that a singlerevolution of the position sensor 472 element corresponds to some linearlongitudinal translation of the displacement member. An arrangement ofgearing and sensors can be connected to the linear actuator, via a rackand pinion arrangement, or a rotary actuator, via a spur gear or otherconnection. A power source supplies power to the absolute positioningsystem and an output indicator may display the output of the absolutepositioning system. The displacement member represents thelongitudinally movable drive member comprising a rack of drive teethformed thereon for meshing engagement with a corresponding drive gear ofthe gear reducer assembly. The displacement member represents thelongitudinally movable firing member to open and close a clamp arm.

A single revolution of the sensor element associated with the positionsensor 472 is equivalent to a longitudinal linear displacement d₁ of theof the displacement member, where d₁ is the longitudinal linear distancethat the displacement member moves from point “a” to point “b” after asingle revolution of the sensor element coupled to the displacementmember. The sensor arrangement may be connected via a gear reductionthat results in the position sensor 472 completing one or morerevolutions for the full stroke of the displacement member. The positionsensor 472 may complete multiple revolutions for the full stroke of thedisplacement member.

A series of switches, where n is an integer greater than one, may beemployed alone or in combination with a gear reduction to provide aunique position signal for more than one revolution of the positionsensor 472. The state of the switches are fed back to themicrocontroller 461 that applies logic to determine a unique positionsignal corresponding to the longitudinal linear displacement d₁+d₂+d_(n)of the displacement member. The output of the position sensor 472 isprovided to the microcontroller 461. The position sensor 472 of thesensor arrangement may comprise a magnetic sensor, an analog rotarysensor like a potentiometer, or an array of analog Hall-effect elements,which output a unique combination of position signals or values.

The position sensor 472 may comprise any number of magnetic sensingelements, such as, for example, magnetic sensors classified according towhether they measure the total magnetic field or the vector componentsof the magnetic field. The techniques used to produce both types ofmagnetic sensors encompass many aspects of physics and electronics. Thetechnologies used for magnetic field sensing include search coil,fluxgate, optically pumped, nuclear precession, SQUID, Hall-effect,anisotropic magnetoresistance, giant magnetoresistance, magnetic tunneljunctions, giant magnetoimpedance, magnetostrictive/piezoelectriccomposites, magnetodiode, magnetotransistor, fiber-optic, magneto-optic,and microelectromechanical systems-based magnetic sensors, among others.

In one aspect, the position sensor 472 for the tracking system 480comprising an absolute positioning system comprises a magnetic rotaryabsolute positioning system. The position sensor 472 may be implementedas an AS5055EQFT single-chip magnetic rotary position sensor availablefrom Austria Microsystems, AG. The position sensor 472 is interfacedwith the microcontroller 461 to provide an absolute positioning system.The position sensor 472 is a low-voltage and low-power component andincludes four Hall-effect elements in an area of the position sensor 472that is located above a magnet. A high-resolution ADC and a smart powermanagement controller are also provided on the chip. A coordinaterotation digital computer (CORDIC) processor, also known as thedigit-by-digit method and Volder's algorithm, is provided to implement asimple and efficient algorithm to calculate hyperbolic and trigonometricfunctions that require only addition, subtraction, bitshift, and tablelookup operations. The angle position, alarm bits, and magnetic fieldinformation are transmitted over a standard serial communicationinterface, such as a serial peripheral interface (SPI) interface, to themicrocontroller 461. The position sensor 472 provides 12 or 14 bits ofresolution. The position sensor 472 may be an AS5055 chip provided in asmall QFN 16-pin 4×4×0.85 mm package.

The tracking system 480 comprising an absolute positioning system maycomprise and/or be programmed to implement a feedback controller, suchas a PID, state feedback, and adaptive controller. A power sourceconverts the signal from the feedback controller into a physical inputto the system: in this case the voltage. Other examples include a PWM ofthe voltage, current, and force. Other sensor(s) may be provided tomeasure physical parameters of the physical system in addition to theposition measured by the position sensor 472. In some aspects, the othersensor(s) can include sensor arrangements such as those described inU.S. Pat. No. 9,345,481, titled STAPLE CARTRIDGE TISSUE THICKNESS SENSORSYSTEM, which issued on May 24, 2016, which is herein incorporated byreference in its entirety; U.S. Patent Application Publication No.2014/0263552, titled STAPLE CARTRIDGE TISSUE THICKNESS SENSOR SYSTEM,which published on Sep. 18, 2014, which is herein incorporated byreference in its entirety; and U.S. patent application Ser. No.15/628,175, titled TECHNIQUES FOR ADAPTIVE CONTROL OF MOTOR VELOCITY OFA SURGICAL STAPLING AND CUTTING INSTRUMENT, filed Jun. 20, 2017, whichis herein incorporated by reference in its entirety. In a digital signalprocessing system, an absolute positioning system is coupled to adigital data acquisition system where the output of the absolutepositioning system will have a finite resolution and sampling frequency.The absolute positioning system may comprise a compare-and-combinecircuit to combine a computed response with a measured response usingalgorithms, such as a weighted average and a theoretical control loop,that drive the computed response towards the measured response. Thecomputed response of the physical system takes into account propertieslike mass, inertia, viscous friction, inductance resistance, etc., topredict what the states and outputs of the physical system will be byknowing the input.

The absolute positioning system provides an absolute position of thedisplacement member upon power-up of the instrument, without retractingor advancing the displacement member to a reset (zero or home) positionas may be required with conventional rotary encoders that merely countthe number of steps forwards or backwards that the motor 482 has takento infer the position of a device actuator, drive bar, knife, or thelike.

A sensor 474, such as, for example, a strain gauge or a micro-straingauge, is configured to measure one or more parameters of the endeffector, such as, for example, the amplitude of the strain exerted onthe anvil during a clamping operation, which can be indicative of theclosure forces applied to the anvil. The measured strain is converted toa digital signal and provided to the processor 462. Alternatively, or inaddition to the sensor 474, a sensor 476, such as, for example, a loadsensor, can measure the closure force applied by the closure drivesystem to the anvil in a stapler or a clamp arm in an ultrasonic orelectrosurgical instrument. The sensor 476, such as, for example, a loadsensor, can measure the firing force applied to a closure member coupledto a clamp arm of the surgical instrument or tool or the force appliedby a clamp arm to tissue located in the jaws of an ultrasonic orelectrosurgical instrument. Alternatively, a current sensor 478 can beemployed to measure the current drawn by the motor 482. The displacementmember also may be configured to engage a clamp arm to open or close theclamp arm. The force sensor may be configured to measure the clampingforce on tissue. The force required to advance the displacement membercan correspond to the current drawn by the motor 482, for example. Themeasured force is converted to a digital signal and provided to theprocessor 462.

In one form, the strain gauge sensor 474 can be used to measure theforce applied to the tissue by the end effector. A strain gauge can becoupled to the end effector to measure the force on the tissue beingtreated by the end effector. A system for measuring forces applied tothe tissue grasped by the end effector comprises a strain gauge sensor474, such as, for example, a micro-strain gauge, that is configured tomeasure one or more parameters of the end effector, for example. In oneaspect, the strain gauge sensor 474 can measure the amplitude ormagnitude of the strain exerted on a jaw member of an end effectorduring a clamping operation, which can be indicative of the tissuecompression. The measured strain is converted to a digital signal andprovided to a processor 462 of the microcontroller 461. A load sensor476 can measure the force used to operate the knife element, forexample, to cut the tissue captured between the anvil and the staplecartridge. A load sensor 476 can measure the force used to operate theclamp arm element, for example, to capture tissue between the clamp armand an ultrasonic blade or to capture tissue between the clamp arm and ajaw of an electrosurgical instrument. A magnetic field sensor can beemployed to measure the thickness of the captured tissue. Themeasurement of the magnetic field sensor also may be converted to adigital signal and provided to the processor 462.

The measurements of the tissue compression, the tissue thickness, and/orthe force required to close the end effector on the tissue, asrespectively measured by the sensors 474, 476, can be used by themicrocontroller 461 to characterize the selected position of the firingmember and/or the corresponding value of the speed of the firing member.In one instance, a memory 468 may store a technique, an equation, and/ora lookup table which can be employed by the microcontroller 461 in theassessment.

The control system 470 of the surgical instrument or tool also maycomprise wired or wireless communication circuits to communicate withthe modular communication hub as shown in FIGS. 8-11.

FIG. 13 illustrates a control circuit 500 configured to control aspectsof the surgical instrument or tool according to one aspect of thisdisclosure. The control circuit 500 can be configured to implementvarious processes described herein. The control circuit 500 may comprisea microcontroller comprising one or more processors 502 (e.g.,microprocessor, microcontroller) coupled to at least one memory circuit504. The memory circuit 504 stores machine-executable instructions that,when executed by the processor 502, cause the processor 502 to executemachine instructions to implement various processes described herein.The processor 502 may be any one of a number of single-core or multicoreprocessors known in the art. The memory circuit 504 may comprisevolatile and non-volatile storage media. The processor 502 may includean instruction processing unit 506 and an arithmetic unit 508. Theinstruction processing unit may be configured to receive instructionsfrom the memory circuit 504 of this disclosure.

FIG. 14 illustrates a combinational logic circuit 510 configured tocontrol aspects of the surgical instrument or tool according to oneaspect of this disclosure. The combinational logic circuit 510 can beconfigured to implement various processes described herein. Thecombinational logic circuit 510 may comprise a finite state machinecomprising a combinational logic 512 configured to receive dataassociated with the surgical instrument or tool at an input 514, processthe data by the combinational logic 512, and provide an output 516.

FIG. 15 illustrates a sequential logic circuit 520 configured to controlaspects of the surgical instrument or tool according to one aspect ofthis disclosure. The sequential logic circuit 520 or the combinationallogic 522 can be configured to implement various processes describedherein. The sequential logic circuit 520 may comprise a finite statemachine. The sequential logic circuit 520 may comprise a combinationallogic 522, at least one memory circuit 524, and a clock 529, forexample. The at least one memory circuit 524 can store a current stateof the finite state machine. In certain instances, the sequential logiccircuit 520 may be synchronous or asynchronous. The combinational logic522 is configured to receive data associated with the surgicalinstrument or tool from an input 526, process the data by thecombinational logic 522, and provide an output 528. In other aspects,the circuit may comprise a combination of a processor (e.g., processor502, FIG. 13) and a finite state machine to implement various processesherein. In other aspects, the finite state machine may comprise acombination of a combinational logic circuit (e.g., combinational logiccircuit 510, FIG. 14) and the sequential logic circuit 520.

FIG. 16 illustrates a surgical instrument or tool comprising a pluralityof motors which can be activated to perform various functions. Incertain instances, a first motor can be activated to perform a firstfunction, a second motor can be activated to perform a second function,a third motor can be activated to perform a third function, a fourthmotor can be activated to perform a fourth function, and so on. Incertain instances, the plurality of motors of robotic surgicalinstrument 600 can be individually activated to cause firing, closure,and/or articulation motions in the end effector. The firing, closure,and/or articulation motions can be transmitted to the end effectorthrough a shaft assembly, for example.

In certain instances, the surgical instrument system or tool may includea firing motor 602. The firing motor 602 may be operably coupled to afiring motor drive assembly 604 which can be configured to transmitfiring motions, generated by the motor 602 to the end effector, inparticular to displace the clamp arm closure member. The closure membermay be retracted by reversing the direction of the motor 602, which alsocauses the clamp arm to open.

In certain instances, the surgical instrument or tool may include aclosure motor 603. The closure motor 603 may be operably coupled to aclosure motor drive assembly 605 which can be configured to transmitclosure motions, generated by the motor 603 to the end effector, inparticular to displace a closure tube to close the anvil and compresstissue between the anvil and the staple cartridge. The closure motor 603may be operably coupled to a closure motor drive assembly 605 which canbe configured to transmit closure motions, generated by the motor 603 tothe end effector, in particular to displace a closure tube to close theclamp arm and compress tissue between the clamp arm and either anultrasonic blade or jaw member of an electrosurgical device. The closuremotions may cause the end effector to transition from an openconfiguration to an approximated configuration to capture tissue, forexample. The end effector may be transitioned to an open position byreversing the direction of the motor 603.

In certain instances, the surgical instrument or tool may include one ormore articulation motors 606 a, 606 b, for example. The motors 606 a,606 b may be operably coupled to respective articulation motor driveassemblies 608 a, 608 b, which can be configured to transmitarticulation motions generated by the motors 606 a, 606 b to the endeffector. In certain instances, the articulation motions may cause theend effector to articulate relative to the shaft, for example.

As described above, the surgical instrument or tool may include aplurality of motors which may be configured to perform variousindependent functions. In certain instances, the plurality of motors ofthe surgical instrument or tool can be individually or separatelyactivated to perform one or more functions while the other motors remaininactive. For example, the articulation motors 606 a, 606 b can beactivated to cause the end effector to be articulated while the firingmotor 602 remains inactive. Alternatively, the firing motor 602 can beactivated to fire the plurality of staples, and/or to advance thecutting edge, while the articulation motor 606 remains inactive.Furthermore, the closure motor 603 may be activated simultaneously withthe firing motor 602 to cause the closure tube or closure member toadvance distally as described in more detail hereinbelow.

In certain instances, the surgical instrument or tool may include acommon control module 610 which can be employed with a plurality ofmotors of the surgical instrument or tool. In certain instances, thecommon control module 610 may accommodate one of the plurality of motorsat a time. For example, the common control module 610 can be couplableto and separable from the plurality of motors of the robotic surgicalinstrument individually. In certain instances, a plurality of the motorsof the surgical instrument or tool may share one or more common controlmodules such as the common control module 610. In certain instances, aplurality of motors of the surgical instrument or tool can beindividually and selectively engaged with the common control module 610.In certain instances, the common control module 610 can be selectivelyswitched from interfacing with one of a plurality of motors of thesurgical instrument or tool to interfacing with another one of theplurality of motors of the surgical instrument or tool.

In at least one example, the common control module 610 can beselectively switched between operable engagement with the articulationmotors 606 a, 606 b and operable engagement with either the firing motor602 or the closure motor 603. In at least one example, as illustrated inFIG. 16, a switch 614 can be moved or transitioned between a pluralityof positions and/or states. In a first position 616, the switch 614 mayelectrically couple the common control module 610 to the firing motor602; in a second position 617, the switch 614 may electrically couplethe common control module 610 to the closure motor 603; in a thirdposition 618 a, the switch 614 may electrically couple the commoncontrol module 610 to the first articulation motor 606 a; and in afourth position 618 b, the switch 614 may electrically couple the commoncontrol module 610 to the second articulation motor 606 b, for example.In certain instances, separate common control modules 610 can beelectrically coupled to the firing motor 602, the closure motor 603, andthe articulations motor 606 a, 606 b at the same time. In certaininstances, the switch 614 may be a mechanical switch, anelectromechanical switch, a solid-state switch, or any suitableswitching mechanism.

Each of the motors 602, 603, 606 a, 606 b may comprise a torque sensorto measure the output torque on the shaft of the motor. The force on anend effector may be sensed in any conventional manner, such as by forcesensors on the outer sides of the jaws or by a torque sensor for themotor actuating the jaws.

In various instances, as illustrated in FIG. 16, the common controlmodule 610 may comprise a motor driver 626 which may comprise one ormore H-Bridge FETs. The motor driver 626 may modulate the powertransmitted from a power source 628 to a motor coupled to the commoncontrol module 610 based on input from a microcontroller 620 (the“controller”), for example. In certain instances, the microcontroller620 can be employed to determine the current drawn by the motor, forexample, while the motor is coupled to the common control module 610, asdescribed above.

In certain instances, the microcontroller 620 may include amicroprocessor 622 (the “processor”) and one or more non-transitorycomputer-readable mediums or memory units 624 (the “memory”). In certaininstances, the memory 624 may store various program instructions, whichwhen executed may cause the processor 622 to perform a plurality offunctions and/or calculations described herein. In certain instances,one or more of the memory units 624 may be coupled to the processor 622,for example. In various aspects, the microcontroller 620 may communicateover a wired or wireless channel, or combinations thereof.

In certain instances, the power source 628 can be employed to supplypower to the microcontroller 620, for example. In certain instances, thepower source 628 may comprise a battery (or “battery pack” or “powerpack”), such as a lithium-ion battery, for example. In certaininstances, the battery pack may be configured to be releasably mountedto a handle for supplying power to the surgical instrument 600. A numberof battery cells connected in series may be used as the power source628. In certain instances, the power source 628 may be replaceableand/or rechargeable, for example.

In various instances, the processor 622 may control the motor driver 626to control the position, direction of rotation, and/or velocity of amotor that is coupled to the common control module 610. In certaininstances, the processor 622 can signal the motor driver 626 to stopand/or disable a motor that is coupled to the common control module 610.It should be understood that the term “processor” as used hereinincludes any suitable microprocessor, microcontroller, or other basiccomputing device that incorporates the functions of a computer's centralprocessing unit (CPU) on an integrated circuit or, at most, a fewintegrated circuits. The processor 622 is a multipurpose, programmabledevice that accepts digital data as input, processes it according toinstructions stored in its memory, and provides results as output. It isan example of sequential digital logic, as it has internal memory.Processors operate on numbers and symbols represented in the binarynumeral system.

In one instance, the processor 622 may be any single-core or multicoreprocessor such as those known under the trade name ARM Cortex by TexasInstruments. In certain instances, the microcontroller 620 may be an LM4F230H5QR, available from Texas Instruments, for example. In at leastone example, the Texas Instruments LM4F230H5QR is an ARM Cortex-M4FProcessor Core comprising an on-chip memory of 256 KB single-cycle flashmemory, or other non-volatile memory, up to 40 MHz, a prefetch buffer toimprove performance above 40 MHz, a 32 KB single-cycle SRAM, an internalROM loaded with StellarisWare® software, a 2 KB EEPROM, one or more PWMmodules, one or more QEI analogs, one or more 12-bit ADCs with 12 analoginput channels, among other features that are readily available for theproduct datasheet. Other microcontrollers may be readily substituted foruse with the module 4410. Accordingly, the present disclosure should notbe limited in this context.

In certain instances, the memory 624 may include program instructionsfor controlling each of the motors of the surgical instrument 600 thatare couplable to the common control module 610. For example, the memory624 may include program instructions for controlling the firing motor602, the closure motor 603, and the articulation motors 606 a, 606 b.Such program instructions may cause the processor 622 to control thefiring, closure, and articulation functions in accordance with inputsfrom algorithms or control programs of the surgical instrument or tool.

In certain instances, one or more mechanisms and/or sensors such as, forexample, sensors 630 can be employed to alert the processor 622 to theprogram instructions that should be used in a particular setting. Forexample, the sensors 630 may alert the processor 622 to use the programinstructions associated with firing, closing, and articulating the endeffector. In certain instances, the sensors 630 may comprise positionsensors which can be employed to sense the position of the switch 614,for example. Accordingly, the processor 622 may use the programinstructions associated with firing the closure member coupled to theclamp arm of the end effector upon detecting, through the sensors 630for example, that the switch 614 is in the first position 616; theprocessor 622 may use the program instructions associated with closingthe anvil upon detecting, through the sensors 630 for example, that theswitch 614 is in the second position 617; and the processor 622 may usethe program instructions associated with articulating the end effectorupon detecting, through the sensors 630 for example, that the switch 614is in the third or fourth position 618 a, 618 b.

FIG. 17 is a schematic diagram of a robotic surgical instrument 700configured to operate a surgical tool described herein according to oneaspect of this disclosure. The robotic surgical instrument 700 may beprogrammed or configured to control distal/proximal translation of adisplacement member, distal/proximal displacement of a closure tube,shaft rotation, and articulation, either with single or multiplearticulation drive links. In one aspect, the surgical instrument 700 maybe programmed or configured to individually control a firing member, aclosure member, a shaft member, or one or more articulation members, orcombinations thereof. The surgical instrument 700 comprises a controlcircuit 710 configured to control motor-driven firing members, closuremembers, shaft members, or one or more articulation members, orcombinations thereof.

In one aspect, the robotic surgical instrument 700 comprises a controlcircuit 710 configured to control a clamp arm 716 and a closure member714 portion of an end effector 702, an ultrasonic blade 718 coupled toan ultrasonic transducer 719 excited by an ultrasonic generator 721, ashaft 740, and one or more articulation members 742 a, 742 b via aplurality of motors 704 a-704 e. A position sensor 734 may be configuredto provide position feedback of the closure member 714 to the controlcircuit 710. Other sensors 738 may be configured to provide feedback tothe control circuit 710. A timer/counter 731 provides timing andcounting information to the control circuit 710. An energy source 712may be provided to operate the motors 704 a-704 e, and a current sensor736 provides motor current feedback to the control circuit 710. Themotors 704 a-704 e can be operated individually by the control circuit710 in an open-loop or closed-loop feedback control.

In one aspect, the control circuit 710 may comprise one or moremicrocontrollers, microprocessors, or other suitable processors forexecuting instructions that cause the processor or processors to performone or more tasks. In one aspect, a timer/counter 731 provides an outputsignal, such as the elapsed time or a digital count, to the controlcircuit 710 to correlate the position of the closure member 714 asdetermined by the position sensor 734 with the output of thetimer/counter 731 such that the control circuit 710 can determine theposition of the closure member 714 at a specific time (t) relative to astarting position or the time (t) when the closure member 714 is at aspecific position relative to a starting position. The timer/counter 731may be configured to measure elapsed time, count external events, ortime external events.

In one aspect, the control circuit 710 may be programmed to controlfunctions of the end effector 702 based on one or more tissueconditions. The control circuit 710 may be programmed to sense tissueconditions, such as thickness, either directly or indirectly, asdescribed herein. The control circuit 710 may be programmed to select afiring control program or closure control program based on tissueconditions. A firing control program may describe the distal motion ofthe displacement member. Different firing control programs may beselected to better treat different tissue conditions. For example, whenthicker tissue is present, the control circuit 710 may be programmed totranslate the displacement member at a lower velocity and/or with lowerpower. When thinner tissue is present, the control circuit 710 may beprogrammed to translate the displacement member at a higher velocityand/or with higher power. A closure control program may control theclosure force applied to the tissue by the clamp arm 716. Other controlprograms control the rotation of the shaft 740 and the articulationmembers 742 a, 742 b.

In one aspect, the control circuit 710 may generate motor set pointsignals. The motor set point signals may be provided to various motorcontrollers 708 a-708 e. The motor controllers 708 a-708 e may compriseone or more circuits configured to provide motor drive signals to themotors 704 a-704 e to drive the motors 704 a-704 e as described herein.In some examples, the motors 704 a-704 e may be brushed DC electricmotors. For example, the velocity of the motors 704 a-704 e may beproportional to the respective motor drive signals. In some examples,the motors 704 a-704 e may be brushless DC electric motors, and therespective motor drive signals may comprise a PWM signal provided to oneor more stator windings of the motors 704 a-704 e. Also, in someexamples, the motor controllers 708 a-708 e may be omitted and thecontrol circuit 710 may generate the motor drive signals directly.

In one aspect, the control circuit 710 may initially operate each of themotors 704 a-704 e in an open-loop configuration for a first open-loopportion of a stroke of the displacement member. Based on the response ofthe robotic surgical instrument 700 during the open-loop portion of thestroke, the control circuit 710 may select a firing control program in aclosed-loop configuration. The response of the instrument may include atranslation distance of the displacement member during the open-loopportion, a time elapsed during the open-loop portion, the energyprovided to one of the motors 704 a-704 e during the open-loop portion,a sum of pulse widths of a motor drive signal, etc. After the open-loopportion, the control circuit 710 may implement the selected firingcontrol program for a second portion of the displacement member stroke.For example, during a closed-loop portion of the stroke, the controlcircuit 710 may modulate one of the motors 704 a-704 e based ontranslation data describing a position of the displacement member in aclosed-loop manner to translate the displacement member at a constantvelocity.

In one aspect, the motors 704 a-704 e may receive power from an energysource 712. The energy source 712 may be a DC power supply driven by amain alternating current power source, a battery, a super capacitor, orany other suitable energy source. The motors 704 a-704 e may bemechanically coupled to individual movable mechanical elements such asthe closure member 714, clamp arm 716, shaft 740, articulation 742 a,and articulation 742 b via respective transmissions 706 a-706 e. Thetransmissions 706 a-706 e may include one or more gears or other linkagecomponents to couple the motors 704 a-704 e to movable mechanicalelements. A position sensor 734 may sense a position of the closuremember 714. The position sensor 734 may be or include any type of sensorthat is capable of generating position data that indicate a position ofthe closure member 714. In some examples, the position sensor 734 mayinclude an encoder configured to provide a series of pulses to thecontrol circuit 710 as the closure member 714 translates distally andproximally. The control circuit 710 may track the pulses to determinethe position of the closure member 714. Other suitable position sensorsmay be used, including, for example, a proximity sensor. Other types ofposition sensors may provide other signals indicating motion of theclosure member 714. Also, in some examples, the position sensor 734 maybe omitted. Where any of the motors 704 a-704 e is a stepper motor, thecontrol circuit 710 may track the position of the closure member 714 byaggregating the number and direction of steps that the motor 704 hasbeen instructed to execute. The position sensor 734 may be located inthe end effector 702 or at any other portion of the instrument. Theoutputs of each of the motors 704 a-704 e include a torque sensor 744a-744 e to sense force and have an encoder to sense rotation of thedrive shaft.

In one aspect, the control circuit 710 is configured to drive a firingmember such as the closure member 714 portion of the end effector 702.The control circuit 710 provides a motor set point to a motor control708 a, which provides a drive signal to the motor 704 a. The outputshaft of the motor 704 a is coupled to a torque sensor 744 a. The torquesensor 744 a is coupled to a transmission 706 a which is coupled to theclosure member 714. The transmission 706 a comprises movable mechanicalelements such as rotating elements and a firing member to control themovement of the closure member 714 distally and proximally along alongitudinal axis of the end effector 702. In one aspect, the motor 704a may be coupled to the knife gear assembly, which includes a knife gearreduction set that includes a first knife drive gear and a second knifedrive gear. A torque sensor 744 a provides a firing force feedbacksignal to the control circuit 710. The firing force signal representsthe force required to fire or displace the closure member 714. Aposition sensor 734 may be configured to provide the position of theclosure member 714 along the firing stroke or the position of the firingmember as a feedback signal to the control circuit 710. The end effector702 may include additional sensors 738 configured to provide feedbacksignals to the control circuit 710. When ready to use, the controlcircuit 710 may provide a firing signal to the motor control 708 a. Inresponse to the firing signal, the motor 704 a may drive the firingmember distally along the longitudinal axis of the end effector 702 froma proximal stroke start position to a stroke end position distal to thestroke start position. As the closure member 714 translates distally,the clamp arm 716 closes towards the ultrasonic blade 718.

In one aspect, the control circuit 710 is configured to drive a closuremember such as the clamp arm 716 portion of the end effector 702. Thecontrol circuit 710 provides a motor set point to a motor control 708 b,which provides a drive signal to the motor 704 b. The output shaft ofthe motor 704 b is coupled to a torque sensor 744 b. The torque sensor744 b is coupled to a transmission 706 b which is coupled to the clamparm 716. The transmission 706 b comprises movable mechanical elementssuch as rotating elements and a closure member to control the movementof the clamp arm 716 from the open and closed positions. In one aspect,the motor 704 b is coupled to a closure gear assembly, which includes aclosure reduction gear set that is supported in meshing engagement withthe closure spur gear. The torque sensor 744 b provides a closure forcefeedback signal to the control circuit 710. The closure force feedbacksignal represents the closure force applied to the clamp arm 716. Theposition sensor 734 may be configured to provide the position of theclosure member as a feedback signal to the control circuit 710.Additional sensors 738 in the end effector 702 may provide the closureforce feedback signal to the control circuit 710. The pivotable clamparm 716 is positioned opposite the ultrasonic blade 718. When ready touse, the control circuit 710 may provide a closure signal to the motorcontrol 708 b. In response to the closure signal, the motor 704 badvances a closure member to grasp tissue between the clamp arm 716 andthe ultrasonic blade 718.

In one aspect, the control circuit 710 is configured to rotate a shaftmember such as the shaft 740 to rotate the end effector 702. The controlcircuit 710 provides a motor set point to a motor control 708 c, whichprovides a drive signal to the motor 704 c. The output shaft of themotor 704 c is coupled to a torque sensor 744 c. The torque sensor 744 cis coupled to a transmission 706 c which is coupled to the shaft 740.The transmission 706 c comprises movable mechanical elements such asrotating elements to control the rotation of the shaft 740 clockwise orcounterclockwise up to and over 360°. In one aspect, the motor 704 c iscoupled to the rotational transmission assembly, which includes a tubegear segment that is formed on (or attached to) the proximal end of theproximal closure tube for operable engagement by a rotational gearassembly that is operably supported on the tool mounting plate. Thetorque sensor 744 c provides a rotation force feedback signal to thecontrol circuit 710. The rotation force feedback signal represents therotation force applied to the shaft 740. The position sensor 734 may beconfigured to provide the position of the closure member as a feedbacksignal to the control circuit 710. Additional sensors 738 such as ashaft encoder may provide the rotational position of the shaft 740 tothe control circuit 710.

In one aspect, the control circuit 710 is configured to articulate theend effector 702. The control circuit 710 provides a motor set point toa motor control 708 d, which provides a drive signal to the motor 704 d.The output shaft of the motor 704 d is coupled to a torque sensor 744 d.The torque sensor 744 d is coupled to a transmission 706 d which iscoupled to an articulation member 742 a. The transmission 706 dcomprises movable mechanical elements such as articulation elements tocontrol the articulation of the end effector 702 ±65°. In one aspect,the motor 704 d is coupled to an articulation nut, which is rotatablyjournaled on the proximal end portion of the distal spine portion and isrotatably driven thereon by an articulation gear assembly. The torquesensor 744 d provides an articulation force feedback signal to thecontrol circuit 710. The articulation force feedback signal representsthe articulation force applied to the end effector 702. Sensors 738,such as an articulation encoder, may provide the articulation positionof the end effector 702 to the control circuit 710.

In another aspect, the articulation function of the robotic surgicalsystem 700 may comprise two articulation members, or links, 742 a, 742b. These articulation members 742 a, 742 b are driven by separate diskson the robot interface (the rack) which are driven by the two motors 708d, 708 e. When the separate firing motor 704 a is provided, each ofarticulation links 742 a, 742 b can be antagonistically driven withrespect to the other link in order to provide a resistive holding motionand a load to the head when it is not moving and to provide anarticulation motion as the head is articulated. The articulation members742 a, 742 b attach to the head at a fixed radius as the head isrotated. Accordingly, the mechanical advantage of the push-and-pull linkchanges as the head is rotated. This change in the mechanical advantagemay be more pronounced with other articulation link drive systems.

In one aspect, the one or more motors 704 a-704 e may comprise a brushedDC motor with a gearbox and mechanical links to a firing member, closuremember, or articulation member. Another example includes electric motors704 a-704 e that operate the movable mechanical elements such as thedisplacement member, articulation links, closure tube, and shaft. Anoutside influence is an unmeasured, unpredictable influence of thingslike tissue, surrounding bodies, and friction on the physical system.Such outside influence can be referred to as drag, which acts inopposition to one of electric motors 704 a-704 e. The outside influence,such as drag, may cause the operation of the physical system to deviatefrom a desired operation of the physical system.

In one aspect, the position sensor 734 may be implemented as an absolutepositioning system. In one aspect, the position sensor 734 may comprisea magnetic rotary absolute positioning system implemented as anAS5055EQFT single-chip magnetic rotary position sensor available fromAustria Microsystems, AG. The position sensor 734 may interface with thecontrol circuit 710 to provide an absolute positioning system. Theposition may include multiple Hall-effect elements located above amagnet and coupled to a CORDIC processor, also known as thedigit-by-digit method and Volder's algorithm, that is provided toimplement a simple and efficient algorithm to calculate hyperbolic andtrigonometric functions that require only addition, subtraction,bitshift, and table lookup operations.

In one aspect, the control circuit 710 may be in communication with oneor more sensors 738. The sensors 738 may be positioned on the endeffector 702 and adapted to operate with the robotic surgical instrument700 to measure the various derived parameters such as the gap distanceversus time, tissue compression versus time, and anvil strain versustime. The sensors 738 may comprise a magnetic sensor, a magnetic fieldsensor, a strain gauge, a load cell, a pressure sensor, a force sensor,a torque sensor, an inductive sensor such as an eddy current sensor, aresistive sensor, a capacitive sensor, an optical sensor, and/or anyother suitable sensor for measuring one or more parameters of the endeffector 702. The sensors 738 may include one or more sensors. Thesensors 738 may be located on the clamp arm 716 to determine tissuelocation using segmented electrodes. The torque sensors 744 a-744 e maybe configured to sense force such as firing force, closure force, and/orarticulation force, among others. Accordingly, the control circuit 710can sense (1) the closure load experienced by the distal closure tubeand its position, (2) the firing member at the rack and its position,(3) what portion of the ultrasonic blade 718 has tissue on it, and (4)the load and position on both articulation rods.

In one aspect, the one or more sensors 738 may comprise a strain gauge,such as a micro-strain gauge, configured to measure the magnitude of thestrain in the clamp arm 716 during a clamped condition. The strain gaugeprovides an electrical signal whose amplitude varies with the magnitudeof the strain. The sensors 738 may comprise a pressure sensor configuredto detect a pressure generated by the presence of compressed tissuebetween the clamp arm 716 and the ultrasonic blade 718. The sensors 738may be configured to detect impedance of a tissue section locatedbetween the clamp arm 716 and the ultrasonic blade 718 that isindicative of the thickness and/or fullness of tissue locatedtherebetween.

In one aspect, the sensors 738 may be implemented as one or more limitswitches, electromechanical devices, solid-state switches, Hall-effectdevices, magneto-resistive (MR) devices, giant magneto-resistive (GMR)devices, magnetometers, among others. In other implementations, thesensors 738 may be implemented as solid-state switches that operateunder the influence of light, such as optical sensors, IR sensors,ultraviolet sensors, among others. Still, the switches may besolid-state devices such as transistors (e.g., FET, junction FET,MOSFET, bipolar, and the like). In other implementations, the sensors738 may include electrical conductorless switches, ultrasonic switches,accelerometers, and inertial sensors, among others.

In one aspect, the sensors 738 may be configured to measure forcesexerted on the clamp arm 716 by the closure drive system. For example,one or more sensors 738 can be at an interaction point between theclosure tube and the clamp arm 716 to detect the closure forces appliedby the closure tube to the clamp arm 716. The forces exerted on theclamp arm 716 can be representative of the tissue compressionexperienced by the tissue section captured between the clamp arm 716 andthe ultrasonic blade 718. The one or more sensors 738 can be positionedat various interaction points along the closure drive system to detectthe closure forces applied to the clamp arm 716 by the closure drivesystem. The one or more sensors 738 may be sampled in real time during aclamping operation by the processor of the control circuit 710. Thecontrol circuit 710 receives real-time sample measurements to provideand analyze time-based information and assess, in real time, closureforces applied to the clamp arm 716.

In one aspect, a current sensor 736 can be employed to measure thecurrent drawn by each of the motors 704 a-704 e. The force required toadvance any of the movable mechanical elements such as the closuremember 714 corresponds to the current drawn by one of the motors 704a-704 e. The force is converted to a digital signal and provided to thecontrol circuit 710. The control circuit 710 can be configured tosimulate the response of the actual system of the instrument in thesoftware of the controller. A displacement member can be actuated tomove the closure member 714 in the end effector 702 at or near a targetvelocity. The robotic surgical instrument 700 can include a feedbackcontroller, which can be one of any feedback controllers, including, butnot limited to a PID, a state feedback, a linear-quadratic (LQR), and/oran adaptive controller, for example. The robotic surgical instrument 700can include a power source to convert the signal from the feedbackcontroller into a physical input such as case voltage, PWM voltage,frequency modulated voltage, current, torque, and/or force, for example.Additional details are disclosed in U.S. patent application Ser. No.15/636,829, titled CLOSED LOOP VELOCITY CONTROL TECHNIQUES FOR ROBOTICSURGICAL INSTRUMENT, filed Jun. 29, 2017, which is herein incorporatedby reference in its entirety.

FIG. 18 illustrates a schematic diagram of a surgical instrument 750configured to control the distal translation of a displacement memberaccording to one aspect of this disclosure. In one aspect, the surgicalinstrument 750 is programmed to control the distal translation of adisplacement member such as the closure member 764. The surgicalinstrument 750 comprises an end effector 752 that may comprise a clamparm 766, a closure member 764, and an ultrasonic blade 768 coupled to anultrasonic transducer 769 driven by an ultrasonic generator 771.

The position, movement, displacement, and/or translation of a lineardisplacement member, such as the closure member 764, can be measured byan absolute positioning system, sensor arrangement, and position sensor784. Because the closure member 764 is coupled to a longitudinallymovable drive member, the position of the closure member 764 can bedetermined by measuring the position of the longitudinally movable drivemember employing the position sensor 784. Accordingly, in the followingdescription, the position, displacement, and/or translation of theclosure member 764 can be achieved by the position sensor 784 asdescribed herein. A control circuit 760 may be programmed to control thetranslation of the displacement member, such as the closure member 764.The control circuit 760, in some examples, may comprise one or moremicrocontrollers, microprocessors, or other suitable processors forexecuting instructions that cause the processor or processors to controlthe displacement member, e.g., the closure member 764, in the mannerdescribed. In one aspect, a timer/counter 781 provides an output signal,such as the elapsed time or a digital count, to the control circuit 760to correlate the position of the closure member 764 as determined by theposition sensor 784 with the output of the timer/counter 781 such thatthe control circuit 760 can determine the position of the closure member764 at a specific time (t) relative to a starting position. Thetimer/counter 781 may be configured to measure elapsed time, countexternal events, or time external events.

The control circuit 760 may generate a motor set point signal 772. Themotor set point signal 772 may be provided to a motor controller 758.The motor controller 758 may comprise one or more circuits configured toprovide a motor drive signal 774 to the motor 754 to drive the motor 754as described herein. In some examples, the motor 754 may be a brushed DCelectric motor. For example, the velocity of the motor 754 may beproportional to the motor drive signal 774. In some examples, the motor754 may be a brushless DC electric motor and the motor drive signal 774may comprise a PWM signal provided to one or more stator windings of themotor 754. Also, in some examples, the motor controller 758 may beomitted, and the control circuit 760 may generate the motor drive signal774 directly.

The motor 754 may receive power from an energy source 762. The energysource 762 may be or include a battery, a super capacitor, or any othersuitable energy source. The motor 754 may be mechanically coupled to theclosure member 764 via a transmission 756. The transmission 756 mayinclude one or more gears or other linkage components to couple themotor 754 to the closure member 764. A position sensor 784 may sense aposition of the closure member 764. The position sensor 784 may be orinclude any type of sensor that is capable of generating position datathat indicate a position of the closure member 764. In some examples,the position sensor 784 may include an encoder configured to provide aseries of pulses to the control circuit 760 as the closure member 764translates distally and proximally. The control circuit 760 may trackthe pulses to determine the position of the closure member 764. Othersuitable position sensors may be used, including, for example, aproximity sensor. Other types of position sensors may provide othersignals indicating motion of the closure member 764. Also, in someexamples, the position sensor 784 may be omitted. Where the motor 754 isa stepper motor, the control circuit 760 may track the position of theclosure member 764 by aggregating the number and direction of steps thatthe motor 754 has been instructed to execute. The position sensor 784may be located in the end effector 752 or at any other portion of theinstrument.

The control circuit 760 may be in communication with one or more sensors788. The sensors 788 may be positioned on the end effector 752 andadapted to operate with the surgical instrument 750 to measure thevarious derived parameters such as gap distance versus time, tissuecompression versus time, and anvil strain versus time. The sensors 788may comprise a magnetic sensor, a magnetic field sensor, a strain gauge,a pressure sensor, a force sensor, an inductive sensor such as an eddycurrent sensor, a resistive sensor, a capacitive sensor, an opticalsensor, and/or any other suitable sensor for measuring one or moreparameters of the end effector 752. The sensors 788 may include one ormore sensors.

The one or more sensors 788 may comprise a strain gauge, such as amicro-strain gauge, configured to measure the magnitude of the strain inthe clamp arm 766 during a clamped condition. The strain gauge providesan electrical signal whose amplitude varies with the magnitude of thestrain. The sensors 788 may comprise a pressure sensor configured todetect a pressure generated by the presence of compressed tissue betweenthe clamp arm 766 and the ultrasonic blade 768. The sensors 788 may beconfigured to detect impedance of a tissue section located between theclamp arm 766 and the ultrasonic blade 768 that is indicative of thethickness and/or fullness of tissue located therebetween.

The sensors 788 may be is configured to measure forces exerted on theclamp arm 766 by a closure drive system. For example, one or moresensors 788 can be at an interaction point between a closure tube andthe clamp arm 766 to detect the closure forces applied by a closure tubeto the clamp arm 766. The forces exerted on the clamp arm 766 can berepresentative of the tissue compression experienced by the tissuesection captured between the clamp arm 766 and the ultrasonic blade 768.The one or more sensors 788 can be positioned at various interactionpoints along the closure drive system to detect the closure forcesapplied to the clamp arm 766 by the closure drive system. The one ormore sensors 788 may be sampled in real time during a clamping operationby a processor of the control circuit 760. The control circuit 760receives real-time sample measurements to provide and analyze time-basedinformation and assess, in real time, closure forces applied to theclamp arm 766.

A current sensor 786 can be employed to measure the current drawn by themotor 754. The force required to advance the closure member 764corresponds to the current drawn by the motor 754. The force isconverted to a digital signal and provided to the control circuit 760.

The control circuit 760 can be configured to simulate the response ofthe actual system of the instrument in the software of the controller. Adisplacement member can be actuated to move a closure member 764 in theend effector 752 at or near a target velocity. The surgical instrument750 can include a feedback controller, which can be one of any feedbackcontrollers, including, but not limited to a PID, a state feedback, LQR,and/or an adaptive controller, for example. The surgical instrument 750can include a power source to convert the signal from the feedbackcontroller into a physical input such as case voltage, PWM voltage,frequency modulated voltage, current, torque, and/or force, for example.

The actual drive system of the surgical instrument 750 is configured todrive the displacement member, cutting member, or closure member 764, bya brushed DC motor with gearbox and mechanical links to an articulationand/or knife system. Another example is the electric motor 754 thatoperates the displacement member and the articulation driver, forexample, of an interchangeable shaft assembly. An outside influence isan unmeasured, unpredictable influence of things like tissue,surrounding bodies and friction on the physical system. Such outsideinfluence can be referred to as drag which acts in opposition to theelectric motor 754. The outside influence, such as drag, may cause theoperation of the physical system to deviate from a desired operation ofthe physical system.

Various example aspects are directed to a surgical instrument 750comprising an end effector 752 with motor-driven surgical sealing andcutting implements. For example, a motor 754 may drive a displacementmember distally and proximally along a longitudinal axis of the endeffector 752. The end effector 752 may comprise a pivotable clamp arm766 and, when configured for use, an ultrasonic blade 768 positionedopposite the clamp arm 766. A clinician may grasp tissue between theclamp arm 766 and the ultrasonic blade 768, as described herein. Whenready to use the instrument 750, the clinician may provide a firingsignal, for example by depressing a trigger of the instrument 750. Inresponse to the firing signal, the motor 754 may drive the displacementmember distally along the longitudinal axis of the end effector 752 froma proximal stroke begin position to a stroke end position distal of thestroke begin position. As the displacement member translates distally,the closure member 764 with a cutting element positioned at a distalend, may cut the tissue between the ultrasonic blade 768 and the clamparm 766.

In various examples, the surgical instrument 750 may comprise a controlcircuit 760 programmed to control the distal translation of thedisplacement member, such as the closure member 764, for example, basedon one or more tissue conditions. The control circuit 760 may beprogrammed to sense tissue conditions, such as thickness, eitherdirectly or indirectly, as described herein. The control circuit 760 maybe programmed to select a control program based on tissue conditions. Acontrol program may describe the distal motion of the displacementmember. Different control programs may be selected to better treatdifferent tissue conditions. For example, when thicker tissue ispresent, the control circuit 760 may be programmed to translate thedisplacement member at a lower velocity and/or with lower power. Whenthinner tissue is present, the control circuit 760 may be programmed totranslate the displacement member at a higher velocity and/or withhigher power.

In some examples, the control circuit 760 may initially operate themotor 754 in an open loop configuration for a first open loop portion ofa stroke of the displacement member. Based on a response of theinstrument 750 during the open loop portion of the stroke, the controlcircuit 760 may select a firing control program. The response of theinstrument may include, a translation distance of the displacementmember during the open loop portion, a time elapsed during the open loopportion, energy provided to the motor 754 during the open loop portion,a sum of pulse widths of a motor drive signal, etc. After the open loopportion, the control circuit 760 may implement the selected firingcontrol program for a second portion of the displacement member stroke.For example, during the closed loop portion of the stroke, the controlcircuit 760 may modulate the motor 754 based on translation datadescribing a position of the displacement member in a closed loop mannerto translate the displacement member at a constant velocity. Additionaldetails are disclosed in U.S. patent application Ser. No. 15/720,852,titled SYSTEM AND METHODS FOR CONTROLLING A DISPLAY OF A SURGICALINSTRUMENT, filed Sep. 29, 2017, which is herein incorporated byreference in its entirety.

FIG. 19 is a schematic diagram of a surgical instrument 790 configuredto control various functions according to one aspect of this disclosure.In one aspect, the surgical instrument 790 is programmed to controldistal translation of a displacement member such as the closure member764. The surgical instrument 790 comprises an end effector 792 that maycomprise a clamp arm 766, a closure member 764, and an ultrasonic blade768 which may be interchanged with or work in conjunction with one ormore RF electrodes 796 (shown in dashed line). The ultrasonic blade 768is coupled to an ultrasonic transducer 769 driven by an ultrasonicgenerator 771.

In one aspect, sensors 788 may be implemented as a limit switch,electromechanical device, solid-state switches, Hall-effect devices, MRdevices, GMR devices, magnetometers, among others. In otherimplementations, the sensors 638 may be solid-state switches thatoperate under the influence of light, such as optical sensors, IRsensors, ultraviolet sensors, among others. Still, the switches may besolid-state devices such as transistors (e.g., FET, junction FET,MOSFET, bipolar, and the like). In other implementations, the sensors788 may include electrical conductorless switches, ultrasonic switches,accelerometers, and inertial sensors, among others.

In one aspect, the position sensor 784 may be implemented as an absolutepositioning system comprising a magnetic rotary absolute positioningsystem implemented as an AS5055EQFT single-chip magnetic rotary positionsensor available from Austria Microsystems, AG. The position sensor 784may interface with the control circuit 760 to provide an absolutepositioning system. The position may include multiple Hall-effectelements located above a magnet and coupled to a CORDIC processor, alsoknown as the digit-by-digit method and Volder's algorithm, that isprovided to implement a simple and efficient algorithm to calculatehyperbolic and trigonometric functions that require only addition,subtraction, bitshift, and table lookup operations.

In some examples, the position sensor 784 may be omitted. Where themotor 754 is a stepper motor, the control circuit 760 may track theposition of the closure member 764 by aggregating the number anddirection of steps that the motor has been instructed to execute. Theposition sensor 784 may be located in the end effector 792 or at anyother portion of the instrument.

The control circuit 760 may be in communication with one or more sensors788. The sensors 788 may be positioned on the end effector 792 andadapted to operate with the surgical instrument 790 to measure thevarious derived parameters such as gap distance versus time, tissuecompression versus time, and anvil strain versus time. The sensors 788may comprise a magnetic sensor, a magnetic field sensor, a strain gauge,a pressure sensor, a force sensor, an inductive sensor such as an eddycurrent sensor, a resistive sensor, a capacitive sensor, an opticalsensor, and/or any other suitable sensor for measuring one or moreparameters of the end effector 792. The sensors 788 may include one ormore sensors.

An RF energy source 794 is coupled to the end effector 792 and isapplied to the RF electrode 796 when the RF electrode 796 is provided inthe end effector 792 in place of the ultrasonic blade 768 or to work inconjunction with the ultrasonic blade 768. For example, the ultrasonicblade is made of electrically conductive metal and may be employed asthe return path for electrosurgical RF current. The control circuit 760controls the delivery of the RF energy to the RF electrode 796.

Additional details are disclosed in U.S. patent application Ser. No.15/636,096, titled SURGICAL SYSTEM COUPLABLE WITH STAPLE CARTRIDGE ANDRADIO FREQUENCY CARTRIDGE, AND METHOD OF USING SAME, filed Jun. 28,2017, which is herein incorporated by reference in its entirety.

Generator Hardware Adaptive Ultrasonic Blade Control Algorithms

In various aspects smart ultrasonic energy devices may comprise adaptivealgorithms to control the operation of the ultrasonic blade. In oneaspect, the ultrasonic blade adaptive control algorithms are configuredto identify tissue type and adjust device parameters. In one aspect, theultrasonic blade control algorithms are configured to parameterizetissue type. An algorithm to detect the collagen/elastic ratio of tissueto tune the amplitude of the distal tip of the ultrasonic blade isdescribed in the following section of the present disclosure. Variousaspects of smart ultrasonic energy devices are described herein inconnection with FIGS. 1-85, for example. Accordingly, the followingdescription of adaptive ultrasonic blade control algorithms should beread in conjunction with FIGS. 1-85 and the description associatedtherewith.

Tissue Type Identification And Device Parameter Adjustments

In certain surgical procedures it would be desirable to employ adaptiveultrasonic blade control algorithms. In one aspect, adaptive ultrasonicblade control algorithms may be employed to adjust the parameters of theultrasonic device based on the type of tissue in contact with theultrasonic blade. In one aspect, the parameters of the ultrasonic devicemay be adjusted based on the location of the tissue within the jaws ofthe ultrasonic end effector, for example, the location of the tissuebetween the clamp arm and the ultrasonic blade. The impedance of theultrasonic transducer may be employed to differentiate what percentageof the tissue is located in the distal or proximal end of the endeffector. The reactions of the ultrasonic device may be based on thetissue type or compressibility of the tissue. In another aspect, theparameters of the ultrasonic device may be adjusted based on theidentified tissue type or parameterization. For example, the mechanicaldisplacement amplitude of the distal tip of the ultrasonic blade may betuned based on the ration of collagen to elastin tissue detected duringthe tissue identification procedure. The ratio of collagen to elastintissue may be detected used a variety of techniques including infrared(IR) surface reflectance and emissivity. The force applied to the tissueby the clamp arm and/or the stroke of the clamp arm to produce gap andcompression. Electrical continuity across a jaw equipped with electrodesmay be employed to determine what percentage of the jaw is covered withtissue.

FIG. 20 is a system 800 configured to execute adaptive ultrasonic bladecontrol algorithms in a surgical data network comprising a modularcommunication hub, in accordance with at least one aspect of the presentdisclosure. In one aspect, the generator module 240 is configured toexecute the adaptive ultrasonic blade control algorithm(s) 802 asdescribed herein with reference to FIGS. 43A-54. In another aspect, thedevice/instrument 235 is configured to execute the adaptive ultrasonicblade control algorithm(s) 804 as described herein with reference toFIGS. 43A-54. In another aspect, both the device/instrument 235 and thedevice/instrument 235 are configured to execute the adaptive ultrasonicblade control algorithms 802,804 as described herein with reference toFIGS. 43A-54.

The generator module 240 may comprise a patient isolated stage incommunication with a non-isolated stage via a power transformer. Asecondary winding of the power transformer is contained in the isolatedstage and may comprise a tapped configuration (e.g., a center-tapped ora non-center-tapped configuration) to define drive signal outputs fordelivering drive signals to different surgical instruments, such as, forexample, an ultrasonic surgical instrument, an RF electrosurgicalinstrument, and a multifunction surgical instrument which includesultrasonic and RF energy modes that can be delivered alone orsimultaneously. In particular, the drive signal outputs may output anultrasonic drive signal (e.g., a 420V root-mean-square (RMS) drivesignal) to an ultrasonic surgical instrument 241, and the drive signaloutputs may output an RF electrosurgical drive signal (e.g., a 100V RMSdrive signal) to an RF electrosurgical instrument 241. Aspects of thegenerator module 240 are described herein with reference to FIGS.21-28B.

The generator module 240 or the device/instrument 235 or both arecoupled to the modular control tower 236 connected to multiple operatingtheater devices such as, for example, intelligent surgical instruments,robots, and other computerized devices located in the operating theater,as described with reference to FIGS. 8-11, for example.

FIG. 21 illustrates an example of a generator 900, which is one form ofa generator configured to couple to an ultrasonic instrument and furtherconfigured to execute adaptive ultrasonic blade control algorithms in asurgical data network comprising a modular communication hub as shown inFIG. 20. The generator 900 is configured to deliver multiple energymodalities to a surgical instrument. The generator 900 provides RF andultrasonic signals for delivering energy to a surgical instrument eitherindependently or simultaneously. The RF and ultrasonic signals may beprovided alone or in combination and may be provided simultaneously. Asnoted above, at least one generator output can deliver multiple energymodalities (e.g., ultrasonic, bipolar or monopolar RF, irreversibleand/or reversible electroporation, and/or microwave energy, amongothers) through a single port, and these signals can be deliveredseparately or simultaneously to the end effector to treat tissue. Thegenerator 900 comprises a processor 902 coupled to a waveform generator904. The processor 902 and waveform generator 904 are configured togenerate a variety of signal waveforms based on information stored in amemory coupled to the processor 902, not shown for clarity ofdisclosure. The digital information associated with a waveform isprovided to the waveform generator 904 which includes one or more DACcircuits to convert the digital input into an analog output. The analogoutput is fed to an amplifier 1106 for signal conditioning andamplification. The conditioned and amplified output of the amplifier 906is coupled to a power transformer 908. The signals are coupled acrossthe power transformer 908 to the secondary side, which is in the patientisolation side. A first signal of a first energy modality is provided tothe surgical instrument between the terminals labeled ENERGY₁ andRETURN. A second signal of a second energy modality is coupled across acapacitor 910 and is provided to the surgical instrument between theterminals labeled ENERGY₂ and RETURN. It will be appreciated that morethan two energy modalities may be output and thus the subscript “n” maybe used to designate that up to n ENERGY_(n) terminals may be provided,where n is a positive integer greater than 1. It also will beappreciated that up to “n” return paths RETURN_(n) may be providedwithout departing from the scope of the present disclosure.

A first voltage sensing circuit 912 is coupled across the terminalslabeled ENERGY₁ and the RETURN path to measure the output voltagetherebetween. A second voltage sensing circuit 924 is coupled across theterminals labeled ENERGY₂ and the RETURN path to measure the outputvoltage therebetween. A current sensing circuit 914 is disposed inseries with the RETURN leg of the secondary side of the powertransformer 908 as shown to measure the output current for either energymodality. If different return paths are provided for each energymodality, then a separate current sensing circuit should be provided ineach return leg. The outputs of the first and second voltage sensingcircuits 912, 924 are provided to respective isolation transformers 916,922 and the output of the current sensing circuit 914 is provided toanother isolation transformer 918. The outputs of the isolationtransformers 916, 928, 922 in the on the primary side of the powertransformer 908 (non-patient isolated side) are provided to a one ormore ADC circuit 926. The digitized output of the ADC circuit 926 isprovided to the processor 902 for further processing and computation.The output voltages and output current feedback information can beemployed to adjust the output voltage and current provided to thesurgical instrument and to compute output impedance, among otherparameters. Input/output communications between the processor 902 andpatient isolated circuits is provided through an interface circuit 920.Sensors also may be in electrical communication with the processor 902by way of the interface circuit 920.

In one aspect, the impedance may be determined by the processor 902 bydividing the output of either the first voltage sensing circuit 912coupled across the terminals labeled ENERGY₁or the second voltagesensing circuit 924 coupled across the terminals labeled ENERGY₂TURN bythe output of the current sensing circuit 914 disposed in series withthe RETURN leg of the secondary side of the power transformer 908. Theoutputs of the first and second voltage sensing circuits 912, 924 areprovided to separate isolations transformers 916, 922 and the output ofthe current sensing circuit 914 is provided to another isolationtransformer 916. The digitized voltage and current sensing measurementsfrom the ADC circuit 926 are provided the processor 902 for computingimpedance. As an example, the first energy modality ENERGY₁ may beultrasonic energy and the second energy modality ENERGY₂ may be RFenergy. Nevertheless, in addition to ultrasonic and bipolar or monopolarRF energy modalities, other energy modalities include irreversibleand/or reversible electroporation and/or microwave energy, among others.Also, although the example illustrated in FIG. 21 shows a single returnpath RETURN may be provided for two or more energy modalities, in otheraspects, multiple return paths RETURN_(n) may be provided for eachenergy modality ENERGY_(n). Thus, as described herein, the ultrasonictransducer impedance may be measured by dividing the output of the firstvoltage sensing circuit 912 by the current sensing circuit 914 and thetissue impedance may be measured by dividing the output of the secondvoltage sensing circuit 924 by the current sensing circuit 914.

As shown in FIG. 21, the generator 900 comprising at least one outputport can include a power transformer 908 with a single output and withmultiple taps to provide power in the form of one or more energymodalities, such as ultrasonic, bipolar or monopolar RF, irreversibleand/or reversible electroporation, and/or microwave energy, amongothers, for example, to the end effector depending on the type oftreatment of tissue being performed. For example, the generator 900 candeliver energy with higher voltage and lower current to drive anultrasonic transducer, with lower voltage and higher current to drive RFelectrodes for sealing tissue, or with a coagulation waveform for spotcoagulation using either monopolar or bipolar RF electrosurgicalelectrodes. The output waveform from the generator 900 can be steered,switched, or filtered to provide the frequency to the end effector ofthe surgical instrument. The connection of an ultrasonic transducer tothe generator 900 output would be preferably located between the outputlabeled ENERGY₁ and RETURN as shown in FIG. 21. In one example, aconnection of RF bipolar electrodes to the generator 900 output would bepreferably located between the output labeled ENERGY₂ and RETURN. In thecase of monopolar output, the preferred connections would be activeelectrode (e.g., pencil or other probe) to the ENERGY₂ output and asuitable return pad connected to the RETURN output.

Additional details are disclosed in U.S. Patent Application PublicationNo. 2017/0086914, titled TECHNIQUES FOR OPERATING GENERATOR FORDIGITALLY GENERATING ELECTRICAL SIGNAL WAVEFORMS AND SURGICALINSTRUMENTS, which published on Mar. 30, 2017, which is hereinincorporated by reference in its entirety.

As used throughout this description, the term “wireless” and itsderivatives may be used to describe circuits, devices, systems, methods,techniques, communications channels, etc., that may communicate datathrough the use of modulated electromagnetic radiation through anon-solid medium. The term does not imply that the associated devices donot contain any wires, although in some aspects they might not. Thecommunication module may implement any of a number of wireless or wiredcommunication standards or protocols, including but not limited to W-Fi(IEEE 802.11 family), WiMAX (IEEE A802.16 family), IEEE 802.20, longterm evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPRS,CDMA, TDMA, DECT, Bluetooth, Ethernet derivatives thereof, as well asany other wireless and wired protocols that are designated as 3G, 4G,5G, and beyond. The computing module may include a plurality ofcommunication modules. For instance, a first communication module may bededicated to shorter range wireless communications such as Wi-Fi andBluetooth and a second communication module may be dedicated to longerrange wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE,Ev-DO, and others.

As used herein a processor or processing unit is an electronic circuitwhich performs operations on some external data source, usually memoryor some other data stream. The term is used herein to refer to thecentral processor (central processing unit) in a system or computersystems (especially systems on a chip (SoCs)) that combine a number ofspecialized “processors.”

As used herein, a system on a chip or system on chip (SoC or SOC) is anintegrated circuit (also known as an “IC” or “chip”) that integrates allcomponents of a computer or other electronic systems. It may containdigital, analog, mixed-signal, and often radio-frequency functions—allon a single substrate. A SoC integrates a microcontroller (ormicroprocessor) with advanced peripherals like graphics processing unit(GPU), Wi-Fi module, or coprocessor. A SoC may or may not containbuilt-in memory.

As used herein, a microcontroller or controller is a system thatintegrates a microprocessor with peripheral circuits and memory. Amicrocontroller (or MCU for microcontroller unit) may be implemented asa small computer on a single integrated circuit. It may be similar to aSoC; an SoC may include a microcontroller as one of its components. Amicrocontroller may contain one or more core processing units (CPUs)along with memory and programmable input/output peripherals. Programmemory in the form of Ferroelectric RAM, NOR flash or OTP ROM is alsooften included on chip, as well as a small amount of RAM.Microcontrollers may be employed for embedded applications, in contrastto the microprocessors used in personal computers or other generalpurpose applications consisting of various discrete chips.

As used herein, the term controller or microcontroller may be astand-alone IC or chip device that interfaces with a peripheral device.This may be a link between two parts of a computer or a controller on anexternal device that manages the operation of (and connection with) thatdevice.

Any of the processors or microcontrollers described herein, may beimplemented by any single core or multicore processor such as thoseknown under the trade name ARM Cortex by Texas Instruments. In oneaspect, the processor may be an LM4F230H5QR ARM Cortex-M4F ProcessorCore, available from Texas Instruments, for example, comprising on-chipmemory of 256 KB single-cycle flash memory, or other non-volatilememory, up to 40 MHz, a prefetch buffer to improve performance above 40MHz, a 32 KB single-cycle serial random access memory (SRAM), internalread-only memory (ROM) loaded with StellarisWare® software, 2 KBelectrically erasable programmable read-only memory (EEPROM), one ormore pulse width modulation (PWM) modules, one or more quadratureencoder inputs (QEI) analog, one or more 12-bit Analog-to-DigitalConverters (ADC) with 12 analog input channels, details of which areavailable for the product datasheet.

In one aspect, the processor may comprise a safety controller comprisingtwo controller-based families such as TMS570 and RM4x known under thetrade name Hercules ARM Cortex R4, also by Texas Instruments. The safetycontroller may be configured specifically for IEC 61508 and ISO 26262safety critical applications, among others, to provide advancedintegrated safety features while delivering scalable performance,connectivity, and memory options.

Modular devices include the modules (as described in connection withFIGS. 3 and 9, for example) that are receivable within a surgical huband the surgical devices or instruments that can be connected to thevarious modules in order to connect or pair with the correspondingsurgical hub. The modular devices include, for example, intelligentsurgical instruments, medical imaging devices, suction/irrigationdevices, smoke evacuators, energy generators, ventilators, insufflators,and displays. The modular devices described herein can be controlled bycontrol algorithms. The control algorithms can be executed on themodular device itself, on the surgical hub to which the particularmodular device is paired, or on both the modular device and the surgicalhub (e.g., via a distributed computing architecture). In someexemplifications, the modular devices' control algorithms control thedevices based on data sensed by the modular device itself (i.e., bysensors in, on, or connected to the modular device). This data can berelated to the patient being operated on (e.g., tissue properties orinsufflation pressure) or the modular device itself (e.g., the rate atwhich a knife is being advanced, motor current, or energy levels). Forexample, a control algorithm for a surgical stapling and cuttinginstrument can control the rate at which the instrument's motor drivesits knife through tissue according to resistance encountered by theknife as it advances.

FIG. 22 illustrates one form of a surgical system 1000 comprising agenerator 1100 and various surgical instruments 1104, 1106, 1108 usabletherewith, where the surgical instrument 1104 is an ultrasonic surgicalinstrument, the surgical instrument 1106 is an RF electrosurgicalinstrument, and the multifunction surgical instrument 1108 is acombination ultrasonic/RF electrosurgical instrument. The generator 1100is configurable for use with a variety of surgical instruments.According to various forms, the generator 1100 may be configurable foruse with different surgical instruments of different types including,for example, ultrasonic surgical instruments 1104, RF electrosurgicalinstruments 1106, and multifunction surgical instruments 1108 thatintegrate RF and ultrasonic energies delivered simultaneously from thegenerator 1100. Although in the form of FIG. 22 the generator 1100 isshown separate from the surgical instruments 1104, 1106, 1108 in oneform, the generator 1100 may be formed integrally with any of thesurgical instruments 1104, 1106, 1108 to form a unitary surgical system.The generator 1100 comprises an input device 1110 located on a frontpanel of the generator 1100 console. The input device 1110 may compriseany suitable device that generates signals suitable for programming theoperation of the generator 1100. The generator 1100 may be configuredfor wired or wireless communication.

The generator 1100 is configured to drive multiple surgical instruments1104, 1106, 1108. The first surgical instrument is an ultrasonicsurgical instrument 1104 and comprises a handpiece 1105 (HP), anultrasonic transducer 1120, a shaft 1126, and an end effector 1122. Theend effector 1122 comprises an ultrasonic blade 1128 acousticallycoupled to the ultrasonic transducer 1120 and a clamp arm 1140. Thehandpiece 1105 comprises a trigger 1143 to operate the clamp arm 1140and a combination of the toggle buttons 1134 a, 1134 b, 1134 c toenergize and drive the ultrasonic blade 1128 or other function. Thetoggle buttons 1134 a, 1134 b, 1134 c can be configured to energize theultrasonic transducer 1120 with the generator 1100.

The generator 1100 also is configured to drive a second surgicalinstrument 1106. The second surgical instrument 1106 is an RFelectrosurgical instrument and comprises a handpiece 1107 (HP), a shaft1127, and an end effector 1124. The end effector 1124 compriseselectrodes in clamp arms 1142 a, 1142 b and return through an electricalconductor portion of the shaft 1127. The electrodes are coupled to andenergized by a bipolar energy source within the generator 1100. Thehandpiece 1107 comprises a trigger 1145 to operate the clamp arms 1142a, 1142 b and an energy button 1135 to actuate an energy switch toenergize the electrodes in the end effector 1124.

The generator 1100 also is configured to drive a multifunction surgicalinstrument 1108. The multifunction surgical instrument 1108 comprises ahandpiece 1109 (HP), a shaft 1129, and an end effector 1125. The endeffector 1125 comprises an ultrasonic blade 1149 and a clamp arm 1146.The ultrasonic blade 1149 is acoustically coupled to the ultrasonictransducer 1120. The handpiece 1109 comprises a trigger 1147 to operatethe clamp arm 1146 and a combination of the toggle buttons 1137 a, 1137b, 1137 c to energize and drive the ultrasonic blade 1149 or otherfunction. The toggle buttons 1137 a, 1137 b, 1137 c can be configured toenergize the ultrasonic transducer 1120 with the generator 1100 andenergize the ultrasonic blade 1149 with a bipolar energy source alsocontained within the generator 1100.

The generator 1100 is configurable for use with a variety of surgicalinstruments. According to various forms, the generator 1100 may beconfigurable for use with different surgical instruments of differenttypes including, for example, the ultrasonic surgical instrument 1104,the RF electrosurgical instrument 1106, and the multifunction surgicalinstrument 1108 that integrates RF and ultrasonic energies deliveredsimultaneously from the generator 1100. Although in the form of FIG. 22the generator 1100 is shown separate from the surgical instruments 1104,1106, 1108, in another form the generator 1100 may be formed integrallywith any one of the surgical instruments 1104, 1106, 1108 to form aunitary surgical system. As discussed above, the generator 1100comprises an input device 1110 located on a front panel of the generator1100 console. The input device 1110 may comprise any suitable devicethat generates signals suitable for programming the operation of thegenerator 1100. The generator 1100 also may comprise one or more outputdevices 1112. Further aspects of generators for digitally generatingelectrical signal waveforms and surgical instruments are described in USpatent publication US-2017-0086914-A1, which is herein incorporated byreference in its entirety.

FIG. 23 is an end effector 1122 of the example ultrasonic device 1104,in accordance with at least one aspect of the present disclosure. Theend effector 1122 may comprise a blade 1128 that may be coupled to theultrasonic transducer 1120 via a wave guide. When driven by theultrasonic transducer 1120, the blade 1128 may vibrate and, when broughtinto contact with tissue, may cut and/or coagulate the tissue, asdescribed herein. According to various aspects, and as illustrated inFIG. 23, the end effector 1122 may also comprise a clamp arm 1140 thatmay be configured for cooperative action with the blade 1128 of the endeffector 1122. With the blade 1128, the clamp arm 1140 may comprise aset of jaws. The clamp arm 1140 may be pivotally connected at a distalend of a shaft 1126 of the instrument portion 1104. The clamp arm 1140may include a clamp arm tissue pad 1163, which may be formed fromTEFLON® or other suitable low-friction material. The pad 1163 may bemounted for cooperation with the blade 1128, with pivotal movement ofthe clamp arm 1140 positioning the clamp pad 1163 in substantiallyparallel relationship to, and in contact with, the blade 1128. By thisconstruction, a tissue bite to be clamped may be grasped between thetissue pad 1163 and the blade 1128. The tissue pad 1163 may be providedwith a sawtooth-like configuration including a plurality of axiallyspaced, proximally extending gripping teeth 1161 to enhance the grippingof tissue in cooperation with the blade 1128. The clamp arm 1140 maytransition from the open position shown in FIG. 23 to a closed position(with the clamp arm 1140 in contact with or proximity to the blade 1128)in any suitable manner. For example, the handpiece 1105 may comprise ajaw closure trigger. When actuated by a clinician, the jaw closuretrigger may pivot the clamp arm 1140 in any suitable manner.

The generator 1100 may be activated to provide the drive signal to theultrasonic transducer 1120 in any suitable manner. For example, thegenerator 1100 may comprise a foot switch 1430 (FIG. 24) coupled to thegenerator 1100 via a footswitch cable 1432. A clinician may activate theultrasonic transducer 1120, and thereby the ultrasonic transducer 1120and blade 1128, by depressing the foot switch 1430. In addition, orinstead of the foot switch 1430, some aspects of the device 1104 mayutilize one or more switches positioned on the handpiece 1105 that, whenactivated, may cause the generator 1100 to activate the ultrasonictransducer 1120. In one aspect, for example, the one or more switchesmay comprise a pair of toggle buttons 1134 a, 1134 b, 1134 c (FIG. 22),for example, to determine an operating mode of the device 1104. When thetoggle button 1134 a is depressed, for example, the ultrasonic generator1100 may provide a maximum drive signal to the ultrasonic transducer1120, causing it to produce maximum ultrasonic energy output. Depressingtoggle button 1134 b may cause the ultrasonic generator 1100 to providea user-selectable drive signal to the ultrasonic transducer 1120,causing it to produce less than the maximum ultrasonic energy output.The device 1104 additionally or alternatively may comprise a secondswitch to, for example, indicate a position of a jaw closure trigger foroperating the jaws via the clamp arm 1140 of the end effector 1122.Also, in some aspects, the ultrasonic generator 1100 may be activatedbased on the position of the jaw closure trigger, (e.g., as theclinician depresses the jaw closure trigger to close the jaws via theclamp arm 1140, ultrasonic energy may be applied).

Additionally or alternatively, the one or more switches may comprise atoggle button 1134 c that, when depressed, causes the generator 1100 toprovide a pulsed output (FIG. 22). The pulses may be provided at anysuitable frequency and grouping, for example. In certain aspects, thepower level of the pulses may be the power levels associated with togglebuttons 1134 a, 1134 b (maximum, less than maximum), for example.

It will be appreciated that a device 1104 may comprise any combinationof the toggle buttons 1134 a, 1134 b, 1134 c (FIG. 22). For example, thedevice 1104 could be configured to have only two toggle buttons: atoggle button 1134 a for producing maximum ultrasonic energy output anda toggle button 1134 c for producing a pulsed output at either themaximum or less than maximum power level per. In this way, the drivesignal output configuration of the generator 1100 could be fivecontinuous signals, or any discrete number of individual pulsed signals(1, 2, 3, 4, or 5). In certain aspects, the specific drive signalconfiguration may be controlled based upon, for example, EEPROM settingsin the generator 1100 and/or user power level selection(s).

In certain aspects, a two-position switch may be provided as analternative to a toggle button 1134 c (FIG. 22). For example, a device1104 may include a toggle button 1134 a for producing a continuousoutput at a maximum power level and a two-position toggle button 1134 b.In a first detented position, toggle button 1134 b may produce acontinuous output at a less than maximum power level, and in a seconddetented position the toggle button 1134 b may produce a pulsed output(e.g., at either a maximum or less than maximum power level, dependingupon the EEPROM settings).

In some aspects, the RF electrosurgical end effector 1124, 1125 (FIG.22) may also comprise a pair of electrodes. The electrodes may be incommunication with the generator 1100, for example, via a cable. Theelectrodes may be used, for example, to measure an impedance of a tissuebite present between the clamp arm 1142 a, 1146 and the blade 1142 b,1149. The generator 1100 may provide a signal (e.g., a non-therapeuticsignal) to the electrodes. The impedance of the tissue bite may befound, for example, by monitoring the current, voltage, etc. of thesignal.

In various aspects, the generator 1100 may comprise several separatefunctional elements, such as modules and/or blocks, as shown in FIG. 24,a diagram of the surgical system 1000 of FIG. 22. Different functionalelements or modules may be configured for driving the different kinds ofsurgical devices 1104, 1106, 1108. For example an ultrasonic generatormodule may drive an ultrasonic device, such as the ultrasonic device1104. An electrosurgery/RF generator module may drive theelectrosurgical device 1106. The modules may generate respective drivesignals for driving the surgical devices 1104, 1106, 1108. In variousaspects, the ultrasonic generator module and/or the electrosurgery/RFgenerator module each may be formed integrally with the generator 1100.Alternatively, one or more of the modules may be provided as a separatecircuit module electrically coupled to the generator 1100. (The modulesare shown in phantom to illustrate this option.) Also, in some aspects,the electrosurgery/RF generator module may be formed integrally with theultrasonic generator module, or vice versa.

In accordance with the described aspects, the ultrasonic generatormodule may produce a drive signal or signals of particular voltages,currents, and frequencies (e.g. 55,500 cycles per second, or Hz). Thedrive signal or signals may be provided to the ultrasonic device 1104,and specifically to the transducer 1120, which may operate, for example,as described above. In one aspect, the generator 1100 may be configuredto produce a drive signal of a particular voltage, current, and/orfrequency output signal that can be stepped with high resolution,accuracy, and repeatability.

In accordance with the described aspects, the electrosurgery/RFgenerator module may generate a drive signal or signals with outputpower sufficient to perform bipolar electrosurgery using radio frequency(RF) energy. In bipolar electrosurgery applications, the drive signalmay be provided, for example, to the electrodes of the electrosurgicaldevice 1106, for example, as described above. Accordingly, the generator1100 may be configured for therapeutic purposes by applying electricalenergy to the tissue sufficient for treating the tissue (e.g.,coagulation, cauterization, tissue welding, etc.).

The generator 1100 may comprise an input device 2150 (FIG. 27B) located,for example, on a front panel of the generator 1100 console. The inputdevice 2150 may comprise any suitable device that generates signalssuitable for programming the operation of the generator 1100. Inoperation, the user can program or otherwise control operation of thegenerator 1100 using the input device 2150. The input device 2150 maycomprise any suitable device that generates signals that can be used bythe generator (e.g., by one or more processors contained in thegenerator) to control the operation of the generator 1100 (e.g.,operation of the ultrasonic generator module and/or electrosurgery/RFgenerator module). In various aspects, the input device 2150 includesone or more of: buttons, switches, thumbwheels, keyboard, keypad, touchscreen monitor, pointing device, remote connection to a general purposeor dedicated computer. In other aspects, the input device 2150 maycomprise a suitable user interface, such as one or more user interfacescreens displayed on a touch screen monitor, for example. Accordingly,by way of the input device 2150, the user can set or program variousoperating parameters of the generator, such as, for example, current(I), voltage (V), frequency (f), and/or period (T) of a drive signal orsignals generated by the ultrasonic generator module and/orelectrosurgery/RF generator module.

The generator 1100 may also comprise an output device 2140 (FIG. 27B)located, for example, on a front panel of the generator 1100 console.The output device 2140 includes one or more devices for providing asensory feedback to a user. Such devices may comprise, for example,visual feedback devices (e.g., an LCD display screen, LED indicators),audio feedback devices (e.g., a speaker, a buzzer) or tactile feedbackdevices (e.g., haptic actuators).

Although certain modules and/or blocks of the generator 1100 may bedescribed by way of example, it can be appreciated that a greater orlesser number of modules and/or blocks may be used and still fall withinthe scope of the aspects. Further, although various aspects may bedescribed in terms of modules and/or blocks to facilitate description,such modules and/or blocks may be implemented by one or more hardwarecomponents, e.g., processors, Digital Signal Processors (DSPs),Programmable Logic Devices (PLDs), Application Specific IntegratedCircuits (ASICs), circuits, registers and/or software components, e.g.,programs, subroutines, logic and/or combinations of hardware andsoftware components.

In one aspect, the ultrasonic generator drive module andelectrosurgery/RF drive module 1110 (FIG. 22) may comprise one or moreembedded applications implemented as firmware, software, hardware, orany combination thereof. The modules may comprise various executablemodules such as software, programs, data, drivers, application programinterfaces (APIs), and so forth. The firmware may be stored innonvolatile memory (NVM), such as in bit-masked read-only memory (ROM)or flash memory. In various implementations, storing the firmware in ROMmay preserve flash memory. The NVM may comprise other types of memoryincluding, for example, programmable ROM (PROM), erasable programmableROM (EPROM), electrically erasable programmable ROM (EEPROM), or batterybacked random-access memory (RAM) such as dynamic RAM (DRAM),Double-Data-Rate DRAM (DDRAM), and/or synchronous DRAM (SDRAM).

In one aspect, the modules comprise a hardware component implemented asa processor for executing program instructions for monitoring variousmeasurable characteristics of the devices 1104, 1106, 1108 andgenerating a corresponding output drive signal or signals for operatingthe devices 1104, 1106, 1108. In aspects in which the generator 1100 isused in conjunction with the device 1104, the drive signal may drive theultrasonic transducer 1120 in cutting and/or coagulation operatingmodes. Electrical characteristics of the device 1104 and/or tissue maybe measured and used to control operational aspects of the generator1100 and/or provided as feedback to the user. In aspects in which thegenerator 1100 is used in conjunction with the device 1106, the drivesignal may supply electrical energy (e.g., RF energy) to the endeffector 1124 in cutting, coagulation and/or desiccation modes.Electrical characteristics of the device 1106 and/or tissue may bemeasured and used to control operational aspects of the generator 1100and/or provided as feedback to the user. In various aspects, aspreviously discussed, the hardware components may be implemented as DSP,PLD, ASIC, circuits, and/or registers. In one aspect, the processor maybe configured to store and execute computer software programinstructions to generate the step function output signals for drivingvarious components of the devices 1104, 1106, 1108, such as theultrasonic transducer 1120 and the end effectors 1122, 1124, 1125.

An electromechanical ultrasonic system includes an ultrasonictransducer, a waveguide, and an ultrasonic blade. The electromechanicalultrasonic system has an initial resonant frequency defined by thephysical properties of the ultrasonic transducer, the waveguide, and theultrasonic blade. The ultrasonic transducer is excited by an alternatingvoltage V_(g)(t) and current I_(g)(t) signal equal to the resonantfrequency of the electromechanical ultrasonic system. When theelectromechanical ultrasonic system is at resonance, the phasedifference between the voltage V_(g)(t) and current I_(g)(t) signals iszero. Stated another way, at resonance the inductive impedance is equalto the capacitive impedance. As the ultrasonic blade heats up, thecompliance of the ultrasonic blade (modeled as an equivalentcapacitance) causes the resonant frequency of the electromechanicalultrasonic system to shift. Thus, the inductive impedance is no longerequal to the capacitive impedance causing a mismatch between the drivefrequency and the resonant frequency of the electromechanical ultrasonicsystem. The system is now operating “off-resonance.” The mismatchbetween the drive frequency and the resonant frequency is manifested asa phase difference between the voltage V_(g)(t) and current I_(g)(t)signals applied to the ultrasonic transducer. The generator electronicscan easily monitor the phase difference between the voltage V_(g)(t) andcurrent I_(g)(t) signals and can continuously adjust the drive frequencyuntil the phase difference is once again zero. At this point, the newdrive frequency is equal to the new resonant frequency of theelectromechanical ultrasonic system. The change in phase and/orfrequency can be used as an indirect measurement of the ultrasonic bladetemperature.

As shown in FIG. 25, the electromechanical properties of the ultrasonictransducer may be modeled as an equivalent circuit comprising a firstbranch having a static capacitance and a second “motional” branch havinga serially connected inductance, resistance and capacitance that definethe electromechanical properties of a resonator. Known ultrasonicgenerators may include a tuning inductor for tuning out the staticcapacitance at a resonant frequency so that substantially all ofgenerator's drive signal current flows into the motional branch.Accordingly, by using a tuning inductor, the generator's drive signalcurrent represents the motional branch current, and the generator isthus able to control its drive signal to maintain the ultrasonictransducer's resonant frequency. The tuning inductor may also transformthe phase impedance plot of the ultrasonic transducer to improve thegenerator's frequency lock capabilities. However, the tuning inductormust be matched with the specific static capacitance of an ultrasonictransducer at the operational resonance frequency. In other words, adifferent ultrasonic transducer having a different static capacitancerequires a different tuning inductor.

FIG. 25 illustrates an equivalent circuit 1500 of an ultrasonictransducer, such as the ultrasonic transducer 1120, according to oneaspect. The circuit 1500 comprises a first “motional” branch having aserially connected inductance L_(s), resistance R_(s) and capacitanceC_(s) that define the electromechanical properties of the resonator, anda second capacitive branch having a static capacitance C₀. Drive currentI_(g)(t) may be received from a generator at a drive voltage V_(g)(t),with motional current I_(m)(t) flowing through the first branch andcurrent I_(g)(t)-I_(m)(t) flowing through the capacitive branch. Controlof the electromechanical properties of the ultrasonic transducer may beachieved by suitably controlling I_(g)(t) and V_(g)(t). As explainedabove, known generator architectures may include a tuning inductor L_(t)(shown in phantom in FIG. 25) in a parallel resonance circuit for tuningout the static capacitance C₀ at a resonant frequency so thatsubstantially all of the generator's current output I_(g)(t) flowsthrough the motional branch. In this way, control of the motional branchcurrent I_(m)(t) is achieved by controlling the generator current outputI_(g)(t). The tuning inductor L_(t) is specific to the staticcapacitance C₀ of an ultrasonic transducer, however, and a differentultrasonic transducer having a different static capacitance requires adifferent tuning inductor L_(t). Moreover, because the tuning inductorL_(t) is matched to the nominal value of the static capacitance C₀ at asingle resonant frequency, accurate control of the motional branchcurrent I_(m)(t) is assured only at that frequency. As frequency shiftsdown with transducer temperature, accurate control of the motionalbranch current is compromised.

Various aspects of the generator 1100 may not rely on a tuning inductorL_(t) to monitor the motional branch current I_(m)(t). Instead, thegenerator 1100 may use the measured value of the static capacitance C₀in between applications of power for a specific ultrasonic surgicaldevice 1104 (along with drive signal voltage and current feedback data)to determine values of the motional branch current I_(m)(t) on a dynamicand ongoing basis (e.g., in real-time). Such aspects of the generator1100 are therefore able to provide virtual tuning to simulate a systemthat is tuned or resonant with any value of static capacitance C₀ at anyfrequency, and not just at a single resonant frequency dictated by anominal value of the static capacitance C₀.

FIG. 26 is a simplified block diagram of one aspect of the generator1100 for providing inductorless tuning as described above, among otherbenefits. FIGS. 27A-27C illustrate an architecture of the generator 1100of FIG. 26 according to one aspect. With reference to FIG. 26, thegenerator 1100 may comprise a patient isolated stage 1520 incommunication with a non-isolated stage 1540 via a power transformer1560. A secondary winding 1580 of the power transformer 1560 iscontained in the isolated stage 1520 and may comprise a tappedconfiguration (e.g., a center-tapped or non-center tapped configuration)to define drive signal outputs 1600 a, 1600 b, 1600 c for outputtingdrive signals to different surgical devices, such as, for example, anultrasonic surgical device 1104 and an electrosurgical device 1106. Inparticular, drive signal outputs 1600 a, 1600 b, 1600 c may output adrive signal (e.g., a 420V RMS drive signal) to an ultrasonic surgicaldevice 1104, and drive signal outputs 1600 a, 1600 b, 1600 c may outputa drive signal (e.g., a 100V RMS drive signal) to an electrosurgicaldevice 1106, with output 1600 b corresponding to the center tap of thepower transformer 1560. The non-isolated stage 1540 may comprise a poweramplifier 1620 having an output connected to a primary winding 1640 ofthe power transformer 1560. In certain aspects the power amplifier 1620may comprise a push-pull amplifier, for example. The non-isolated stage1540 may further comprise a programmable logic device 1660 for supplyinga digital output to a digital-to-analog converter (DAC) 1680, which inturn supplies a corresponding analog signal to an input of the poweramplifier 1620. In certain aspects the programmable logic device 1660may comprise a field-programmable gate array (FPGA), for example. Theprogrammable logic device 1660, by virtue of controlling the poweramplifier's 1620 input via the DAC 1680, may therefore control any of anumber of parameters (e.g., frequency, waveform shape, waveformamplitude) of drive signals appearing at the drive signal outputs 1600a, 1600 b, 1600 c. In certain aspects and as discussed below, theprogrammable logic device 1660, in conjunction with a processor (e.g.,processor 1740 discussed below), may implement a number of digitalsignal processing (DSP)-based and/or other control algorithms to controlparameters of the drive signals output by the generator 1100.

Power may be supplied to a power rail of the power amplifier 1620 by aswitch-mode regulator 1700. In certain aspects the switch-mode regulator1700 may comprise an adjustable buck regulator, for example. Asdiscussed above, the non-isolated stage 1540 may further comprise aprocessor 1740, which in one aspect may comprise a DSP processor such asan ADSP-21469 SHARC DSP, available from Analog Devices, Norwood, Mass.,for example. In certain aspects the processor 1740 may control operationof the switch-mode power converter 1700 responsive to voltage feedbackdata received from the power amplifier 1620 by the processor 1740 via ananalog-to-digital converter (ADC) 1760. In one aspect, for example, theprocessor 1740 may receive as input, via the ADC 1760, the waveformenvelope of a signal (e.g., an RF signal) being amplified by the poweramplifier 1620. The processor 1740 may then control the switch-moderegulator 1700 (e.g., via a pulse-width modulated (PWM) output) suchthat the rail voltage supplied to the power amplifier 1620 tracks thewaveform envelope of the amplified signal. By dynamically modulating therail voltage of the power amplifier 1620 based on the waveform envelope,the efficiency of the power amplifier 1620 may be significantly improvedrelative to a fixed rail voltage amplifier scheme. The processor 1740may be configured for wired or wireless communication.

In certain aspects and as discussed in further detail in connection withFIGS. 28A-28B, the programmable logic device 1660, in conjunction withthe processor 1740, may implement a direct digital synthesizer (DDS)control scheme to control the waveform shape, frequency and/or amplitudeof drive signals output by the generator 1100. In one aspect, forexample, the programmable logic device 1660 may implement a DDS controlalgorithm 2680 (FIG. 28A) by recalling waveform samples stored in adynamically-updated look-up table (LUT), such as a RAM LUT which may beembedded in an FPGA. This control algorithm is particularly useful forultrasonic applications in which an ultrasonic transducer, such as theultrasonic transducer 1120, may be driven by a clean sinusoidal currentat its resonant frequency. Because other frequencies may exciteparasitic resonances, minimizing or reducing the total distortion of themotional branch current may correspondingly minimize or reduceundesirable resonance effects. Because the waveform shape of a drivesignal output by the generator 1100 is impacted by various sources ofdistortion present in the output drive circuit (e.g., the powertransformer 1560, the power amplifier 1620), voltage and currentfeedback data based on the drive signal may be input into an algorithm,such as an error control algorithm implemented by the processor 1740,which compensates for distortion by suitably pre-distorting or modifyingthe waveform samples stored in the LUT on a dynamic, ongoing basis(e.g., in real-time). In one aspect, the amount or degree ofpre-distortion applied to the LUT samples may be based on the errorbetween a computed motional branch current and a desired currentwaveform shape, with the error being determined on a sample-by samplebasis. In this way, the pre-distorted LUT samples, when processedthrough the drive circuit, may result in a motional branch drive signalhaving the desired waveform shape (e.g., sinusoidal) for optimallydriving the ultrasonic transducer. In such aspects, the LUT waveformsamples will therefore not represent the desired waveform shape of thedrive signal, but rather the waveform shape that is required toultimately produce the desired waveform shape of the motional branchdrive signal when distortion effects are taken into account.

The non-isolated stage 1540 may further comprise an ADC 1780 and an ADC1800 coupled to the output of the power transformer 1560 via respectiveisolation transformers 1820, 1840 for respectively sampling the voltageand current of drive signals output by the generator 1100. In certainaspects, the ADCs 1780, 1800 may be configured to sample at high speeds(e.g., 80 Msps) to enable oversampling of the drive signals. In oneaspect, for example, the sampling speed of the ADCs 1780, 1800 mayenable approximately 200× (depending on drive frequency) oversampling ofthe drive signals. In certain aspects, the sampling operations of theADCs 1780, 1800 may be performed by a single ADC receiving input voltageand current signals via a two-way multiplexer. The use of high-speedsampling in aspects of the generator 1100 may enable, among otherthings, calculation of the complex current flowing through the motionalbranch (which may be used in certain aspects to implement DDS-basedwaveform shape control described above), accurate digital filtering ofthe sampled signals, and calculation of real power consumption with ahigh degree of precision. Voltage and current feedback data output bythe ADCs 1780, 1800 may be received and processed (e.g., FIFO buffering,multiplexing) by the programmable logic device 1660 and stored in datamemory for subsequent retrieval by, for example, the processor 1740. Asnoted above, voltage and current feedback data may be used as input toan algorithm for pre-distorting or modifying LUT waveform samples on adynamic and ongoing basis. In certain aspects, this may require eachstored voltage and current feedback data pair to be indexed based on, orotherwise associated with, a corresponding LUT sample that was output bythe programmable logic device 1660 when the voltage and current feedbackdata pair was acquired. Synchronization of the LUT samples and thevoltage and current feedback data in this manner contributes to thecorrect timing and stability of the pre-distortion algorithm.

In certain aspects, the voltage and current feedback data may be used tocontrol the frequency and/or amplitude (e.g., current amplitude) of thedrive signals. In one aspect, for example, voltage and current feedbackdata may be used to determine impedance phase, e.g., the phasedifference between the voltage and current drive signals. The frequencyof the drive signal may then be controlled to minimize or reduce thedifference between the determined impedance phase and an impedance phasesetpoint (e.g., 0°), thereby minimizing or reducing the effects ofharmonic distortion and correspondingly enhancing impedance phasemeasurement accuracy. The determination of phase impedance and afrequency control signal may be implemented in the processor 1740, forexample, with the frequency control signal being supplied as input to aDDS control algorithm implemented by the programmable logic device 1660.

The impedance phase may be determined through Fourier analysis. In oneaspect, the phase difference between the generator voltage V_(g)(t) andgenerator current I_(g)(t) driving signals may be determined using theFast Fourier Transform (FFT) or the Discrete Fourier Transform (DFT) asfollows:

V_(g)(t) = A₁cos (2π f₀t + ϕ₁)I_(g)(t) = A₂cos (2π f₀t + ϕ₂)${V_{g}(f)} = {\frac{A_{1}}{2}\left( {{\delta \left( {f - f_{0}} \right)} + {\delta \left( {f + f_{0}} \right)}} \right){\exp \left( {j\; 2\pi \; f\frac{\phi_{1}}{2\pi \; f_{0}}} \right)}}$${I_{g}(f)} = {\frac{A_{2}}{2}\left( {{\delta \left( {f - f_{0}} \right)} + {\delta \left( {f + f_{0}} \right)}} \right){\exp \left( {j\; 2\pi \; f\frac{\phi_{2}}{2\pi \; f_{0}}} \right)}}$

Evaluating the Fourier Transform at the frequency of the sinusoidyields:

${V_{g}\left( f_{0} \right)} = {{\frac{A_{1}}{2}{\delta (0)}{\exp \left( {j\; \phi_{1}} \right)}\mspace{20mu} \arg \; {V\left( f_{0} \right)}} = \phi_{1}}$${I_{g}\left( f_{0} \right)} = {{\frac{A_{2}}{2}{\delta (0)}{\exp \left( {j\; \phi_{2}} \right)}\mspace{20mu} \arg \; {V\left( f_{0} \right)}} = \phi_{2}}$

Other approaches include weighted least-squares estimation, Kalmanfiltering, and space-vector-based techniques. Virtually all of theprocessing in an FFT or DFT technique may be performed in the digitaldomain with the aid of the 2-channel high speed ADC 1780, 1800, forexample. In one technique, the digital signal samples of the voltage andcurrent signals are Fourier transformed with an FFT or a DFT. The phaseangle φ at any point in time can be calculated by:

φ=2πft+φ ₀

where φ is the phase angle, f is the frequency, t is time, and φ₀ is thephase at t=0.

Another technique for determining the phase difference between thevoltage V_(g)(t) and current I_(g)(t) signals is the zero-crossingmethod and produces highly accurate results. For voltage V_(g)(t) andcurrent I_(g)(t) signals having the same frequency, each negative topositive zero-crossing of voltage signal V_(g)(t) triggers the start ofa pulse, while each negative to positive zero-crossing of current signalI_(g)(t) triggers the end of the pulse. The result is a pulse train witha pulse width proportional to the phase angle between the voltage signaland the current signal. In one aspect, the pulse train may be passedthrough an averaging filter to yield a measure of the phase difference.Furthermore, if the positive to negative zero crossings also are used ina similar manner, and the results averaged, any effects of DC andharmonic components can be reduced. In one implementation, the analogvoltage V_(g)(t) and current I_(g)(t) signals are converted to digitalsignals that are high if the analog signal is positive and low if theanalog signal is negative. High accuracy phase estimates require sharptransitions between high and low. In one aspect, a Schmitt trigger alongwith an RC stabilization network may be employed to convert the analogsignals into digital signals. In other aspects, an edge triggered RSflip-flop and ancillary circuitry may be employed. In yet anotheraspect, the zero-crossing technique may employ an eXclusive OR (XOR)gate.

Other techniques for determining the phase difference between thevoltage and current signals include Lissajous figures and monitoring theimage; methods such as the three-voltmeter method, the crossed-coilmethod, vector voltmeter and vector impedance methods; and using phasestandard instruments, phase-locked loops, and other techniques asdescribed in Phase Measurement, Peter O'Shea, 2000 CRC Press LLC,<http://www.engnetbase.com>, which is incorporated herein by reference.

In another aspect, for example, the current feedback data may bemonitored in order to maintain the current amplitude of the drive signalat a current amplitude setpoint. The current amplitude setpoint may bespecified directly or determined indirectly based on specified voltageamplitude and power setpoints. In certain aspects, control of thecurrent amplitude may be implemented by control algorithm, such as, forexample, a proportional-integral-derivative (PID) control algorithm, inthe processor 1740. Variables controlled by the control algorithm tosuitably control the current amplitude of the drive signal may include,for example, the scaling of the LUT waveform samples stored in theprogrammable logic device 1660 and/or the full-scale output voltage ofthe DAC 1680 (which supplies the input to the power amplifier 1620) viaa DAC 1860.

The non-isolated stage 1540 may further comprise a processor 1900 forproviding, among other things, user interface (UI) functionality. In oneaspect, the processor 1900 may comprise an Atmel AT91 SAM9263 processorhaving an ARM 926EJ-S core, available from Atmel Corporation, San Jose,Calif., for example. Examples of UI functionality supported by theprocessor 1900 may include audible and visual user feedback,communication with peripheral devices (e.g., via a Universal Serial Bus(USB) interface), communication with a foot switch 1430, communicationwith an input device 2150 (e.g., a touch screen display) andcommunication with an output device 2140 (e.g., a speaker). Theprocessor 1900 may communicate with the processor 1740 and theprogrammable logic device (e.g., via a serial peripheral interface (SPI)bus). Although the processor 1900 may primarily support UIfunctionality, it may also coordinate with the processor 1740 toimplement hazard mitigation in certain aspects. For example, theprocessor 1900 may be programmed to monitor various aspects of userinput and/or other inputs (e.g., touch screen inputs 2150, foot switch1430 inputs, temperature sensor inputs 2160) and may disable the driveoutput of the generator 1100 when an erroneous condition is detected.

In certain aspects, both the processor 1740 (FIG. 26, 27A) and theprocessor 1900 (FIG. 26, 27B) may determine and monitor the operatingstate of the generator 1100. For processor 1740, the operating state ofthe generator 1100 may dictate, for example, which control and/ordiagnostic processes are implemented by the processor 1740. Forprocessor 1900, the operating state of the generator 1100 may dictate,for example, which elements of a user interface (e.g., display screens,sounds) are presented to a user. The processors 1740, 1900 mayindependently maintain the current operating state of the generator 1100and recognize and evaluate possible transitions out of the currentoperating state. The processor 1740 may function as the master in thisrelationship and determine when transitions between operating states areto occur. The processor 1900 may be aware of valid transitions betweenoperating states and may confirm if a particular transition isappropriate. For example, when the processor 1740 instructs theprocessor 1900 to transition to a specific state, the processor 1900 mayverify that the requested transition is valid. In the event that arequested transition between states is determined to be invalid by theprocessor 1900, the processor 1900 may cause the generator 1100 to entera failure mode.

The non-isolated stage 1540 may further comprise a controller 1960 (FIG.26, 27B) for monitoring input devices 2150 (e.g., a capacitive touchsensor used for turning the generator 1100 on and off, a capacitivetouch screen). In certain aspects, the controller 1960 may comprise atleast one processor and/or other controller device in communication withthe processor 1900. In one aspect, for example, the controller 1960 maycomprise a processor (e.g., a Mega168 8-bit controller available fromAtmel) configured to monitor user input provided via one or morecapacitive touch sensors. In one aspect, the controller 1960 maycomprise a touch screen controller (e.g., a QT5480 touch screencontroller available from Atmel) to control and manage the acquisitionof touch data from a capacitive touch screen.

In certain aspects, when the generator 1100 is in a “power off” state,the controller 1960 may continue to receive operating power (e.g., via aline from a power supply of the generator 1100, such as the power supply2110 (FIG. 26) discussed below). In this way, the controller 1960 maycontinue to monitor an input device 2150 (e.g., a capacitive touchsensor located on a front panel of the generator 1100) for turning thegenerator 1100 on and off. When the generator 1100 is in the “power off”state, the controller 1960 may wake the power supply (e.g., enableoperation of one or more DC/DC voltage converters 2130 (FIG. 26) of thepower supply 2110) if activation of the “on/off” input device 2150 by auser is detected. The controller 1960 may therefore initiate a sequencefor transitioning the generator 1100 to a “power on” state. Conversely,the controller 1960 may initiate a sequence for transitioning thegenerator 1100 to the “power off” state if activation of the “on/off”input device 2150 is detected when the generator 1100 is in the “poweron” state. In certain aspects, for example, the controller 1960 mayreport activation of the “on/off” input device 2150 to the processor1900, which in turn implements the necessary process sequence fortransitioning the generator 1100 to the “power off” state. In suchaspects, the controller 1960 may have no independent ability for causingthe removal of power from the generator 1100 after its “power on” statehas been established.

In certain aspects, the controller 1960 may cause the generator 1100 toprovide audible or other sensory feedback for alerting the user that a“power on” or “power off” sequence has been initiated. Such an alert maybe provided at the beginning of a “power on” or “power off” sequence andprior to the commencement of other processes associated with thesequence.

In certain aspects, the isolated stage 1520 may comprise an instrumentinterface circuit 1980 to, for example, provide a communicationinterface between a control circuit of a surgical device (e.g., acontrol circuit comprising handpiece switches) and components of thenon-isolated stage 1540, such as, for example, the programmable logicdevice 1660, the processor 1740 and/or the processor 1900. Theinstrument interface circuit 1980 may exchange information withcomponents of the non-isolated stage 1540 via a communication link thatmaintains a suitable degree of electrical isolation between the stages1520, 1540, such as, for example, an infrared (IR)-based communicationlink. Power may be supplied to the instrument interface circuit 1980using, for example, a low-dropout voltage regulator powered by anisolation transformer driven from the non-isolated stage 1540.

In one aspect, the instrument interface circuit 1980 may comprise aprogrammable logic device 2000 (e.g., an FPGA) in communication with asignal conditioning circuit 2020 (FIG. 26 and FIG. 27C). The signalconditioning circuit 2020 may be configured to receive a periodic signalfrom the programmable logic device 2000 (e.g., a 2 kHz square wave) togenerate a bipolar interrogation signal having an identical frequency.The interrogation signal may be generated, for example, using a bipolarcurrent source fed by a differential amplifier. The interrogation signalmay be communicated to a surgical device control circuit (e.g., by usinga conductive pair in a cable that connects the generator 1100 to thesurgical device) and monitored to determine a state or configuration ofthe control circuit. For example, the control circuit may comprise anumber of switches, resistors and/or diodes to modify one or morecharacteristics (e.g., amplitude, rectification) of the interrogationsignal such that a state or configuration of the control circuit isuniquely discernible based on the one or more characteristics. In oneaspect, for example, the signal conditioning circuit 2020 may comprisean ADC for generating samples of a voltage signal appearing acrossinputs of the control circuit resulting from passage of interrogationsignal therethrough. The programmable logic device 2000 (or a componentof the non-isolated stage 1540) may then determine the state orconfiguration of the control circuit based on the ADC samples.

In one aspect, the instrument interface circuit 1980 may comprise afirst data circuit interface 2040 to enable information exchange betweenthe programmable logic device 2000 (or other element of the instrumentinterface circuit 1980) and a first data circuit disposed in orotherwise associated with a surgical device. In certain aspects, forexample, a first data circuit 2060 may be disposed in a cable integrallyattached to a surgical device handpiece, or in an adaptor forinterfacing a specific surgical device type or model with the generator1100. In certain aspects, the first data circuit may comprise anon-volatile storage device, such as an electrically erasableprogrammable read-only memory (EEPROM) device. In certain aspects andreferring again to FIG. 26, the first data circuit interface 2040 may beimplemented separately from the programmable logic device 2000 andcomprise suitable circuitry (e.g., discrete logic devices, a processor)to enable communication between the programmable logic device 2000 andthe first data circuit. In other aspects, the first data circuitinterface 2040 may be integral with the programmable logic device 2000.

In certain aspects, the first data circuit 2060 may store informationpertaining to the particular surgical device with which it isassociated. Such information may include, for example, a model number, aserial number, a number of operations in which the surgical device hasbeen used, and/or any other type of information. This information may beread by the instrument interface circuit 1980 (e.g., by the programmablelogic device 2000), transferred to a component of the non-isolated stage1540 (e.g., to programmable logic device 1660, processor 1740 and/orprocessor 1900) for presentation to a user via an output device 2140and/or for controlling a function or operation of the generator 1100.Additionally, any type of information may be communicated to first datacircuit 2060 for storage therein via the first data circuit interface2040 (e.g., using the programmable logic device 2000). Such informationmay comprise, for example, an updated number of operations in which thesurgical device has been used and/or dates and/or times of its usage.

As discussed previously, a surgical instrument may be detachable from ahandpiece (e.g., instrument 1106 may be detachable from handpiece 1107)to promote instrument interchangeability and/or disposability. In suchcases, known generators may be limited in their ability to recognizeparticular instrument configurations being used and to optimize controland diagnostic processes accordingly. The addition of readable datacircuits to surgical device instruments to address this issue isproblematic from a compatibility standpoint, however. For example, itmay be impractical to design a surgical device to maintain backwardcompatibility with generators that lack the requisite data readingfunctionality due to, for example, differing signal schemes, designcomplexity and cost. Other aspects of instruments address these concernsby using data circuits that may be implemented in existing surgicalinstruments economically and with minimal design changes to preservecompatibility of the surgical devices with current generator platforms.

Additionally, aspects of the generator 1100 may enable communicationwith instrument-based data circuits. For example, the generator 1100 maybe configured to communicate with a second data circuit (e.g., a datacircuit) contained in an instrument (e.g., instrument 1104, 1106 or1108) of a surgical device. The instrument interface circuit 1980 maycomprise a second data circuit interface 2100 to enable thiscommunication. In one aspect, the second data circuit interface 2100 maycomprise a tri-state digital interface, although other interfaces mayalso be used. In certain aspects, the second data circuit may generallybe any circuit for transmitting and/or receiving data. In one aspect,for example, the second data circuit may store information pertaining tothe particular surgical instrument with which it is associated. Suchinformation may include, for example, a model number, a serial number, anumber of operations in which the surgical instrument has been used,and/or any other type of information. Additionally or alternatively, anytype of information may be communicated to the second data circuit forstorage therein via the second data circuit interface 2100 (e.g., usingthe programmable logic device 2000). Such information may comprise, forexample, an updated number of operations in which the instrument hasbeen used and/or dates and/or times of its usage. In certain aspects,the second data circuit may transmit data acquired by one or moresensors (e.g., an instrument-based temperature sensor). In certainaspects, the second data circuit may receive data from the generator1100 and provide an indication to a user (e.g., an LED indication orother visible indication) based on the received data.

In certain aspects, the second data circuit and the second data circuitinterface 2100 may be configured such that communication between theprogrammable logic device 2000 and the second data circuit can beeffected without the need to provide additional conductors for thispurpose (e.g., dedicated conductors of a cable connecting a handpiece tothe generator 1100). In one aspect, for example, information may becommunicated to and from the second data circuit using a one-wire buscommunication scheme implemented on existing cabling, such as one of theconductors used transmit interrogation signals from the signalconditioning circuit 2020 to a control circuit in a handpiece. In thisway, design changes or modifications to the surgical device that mightotherwise be necessary are minimized or reduced. Moreover, becausedifferent types of communications can be implemented over a commonphysical channel (either with or without frequency-band separation), thepresence of a second data circuit may be “invisible” to generators thatdo not have the requisite data reading functionality, thus enablingbackward compatibility of the surgical device instrument.

In certain aspects, the isolated stage 1520 may comprise at least oneblocking capacitor 2960-1 (FIG. 27C) connected to the drive signaloutput 1600 b to prevent passage of DC current to a patient. A singleblocking capacitor may be required to comply with medical regulations orstandards, for example. While failure in single-capacitor designs isrelatively uncommon, such failure may nonetheless have negativeconsequences. In one aspect, a second blocking capacitor 2960-2 may beprovided in series with the blocking capacitor 2960-1, with currentleakage from a point between the blocking capacitors 2960-1, 2960-2being monitored by, for example, an ADC 2980 for sampling a voltageinduced by leakage current. The samples may be received by theprogrammable logic device 2000, for example. Based on changes in theleakage current (as indicated by the voltage samples in the aspect ofFIG. 26), the generator 1100 may determine when at least one of theblocking capacitors 2960-1, 2960-2 has failed. Accordingly, the aspectof FIG. 26 may provide a benefit over single-capacitor designs having asingle point of failure.

In certain aspects, the non-isolated stage 1540 may comprise a powersupply 2110 for outputting DC power at a suitable voltage and current.The power supply may comprise, for example, a 400 W power supply foroutputting a 48 VDC system voltage. As discussed above, the power supply2110 may further comprise one or more DC/DC voltage converters 2130 forreceiving the output of the power supply to generate DC outputs at thevoltages and currents required by the various components of thegenerator 1100. As discussed above in connection with the controller1960, one or more of the DC/DC voltage converters 2130 may receive aninput from the controller 1960 when activation of the “on/off” inputdevice 2150 by a user is detected by the controller 1960 to enableoperation of, or wake, the DC/DC voltage converters 2130.

FIGS. 28A-28B illustrate certain functional and structural aspects ofone aspect of the generator 1100. Feedback indicating current andvoltage output from the secondary winding 1580 of the power transformer1560 is received by the ADCs 1780, 1800, respectively. As shown, theADCs 1780, 1800 may be implemented as a 2-channel ADC and may sample thefeedback signals at a high speed (e.g., 80 Msps) to enable oversampling(e.g., approximately 200× oversampling) of the drive signals. Thecurrent and voltage feedback signals may be suitably conditioned in theanalog domain (e.g., amplified, filtered) prior to processing by theADCs 1780, 1800. Current and voltage feedback samples from the ADCs1780, 1800 may be individually buffered and subsequently multiplexed orinterleaved into a single data stream within block 2120 of theprogrammable logic device 1660. In the aspect of FIGS. 28A-28B, theprogrammable logic device 1660 comprises an FPGA.

The multiplexed current and voltage feedback samples may be received bya parallel data acquisition port (PDAP) implemented within block 2144 ofthe processor 1740. The PDAP may comprise a packing unit forimplementing any of a number of methodologies for correlating themultiplexed feedback samples with a memory address. In one aspect, forexample, feedback samples corresponding to a particular LUT sampleoutput by the programmable logic device 1660 may be stored at one ormore memory addresses that are correlated or indexed with the LUTaddress of the LUT sample. In another aspect, feedback samplescorresponding to a particular LUT sample output by the programmablelogic device 1660 may be stored, along with the LUT address of the LUTsample, at a common memory location. In any event, the feedback samplesmay be stored such that the address of the LUT sample from which aparticular set of feedback samples originated may be subsequentlyascertained. As discussed above, synchronization of the LUT sampleaddresses and the feedback samples in this way contributes to thecorrect timing and stability of the pre-distortion algorithm. A directmemory access (DMA) controller implemented at block 2166 of theprocessor 1740 may store the feedback samples (and any LUT sampleaddress data, where applicable) at a designated memory location 2180 ofthe processor 1740 (e.g., internal RAM).

Block 2200 of the processor 1740 may implement a pre-distortionalgorithm for pre-distorting or modifying the LUT samples stored in theprogrammable logic device 1660 on a dynamic, ongoing basis. As discussedabove, pre-distortion of the LUT samples may compensate for varioussources of distortion present in the output drive circuit of thegenerator 1100. The pre-distorted LUT samples, when processed throughthe drive circuit, will therefore result in a drive signal having thedesired waveform shape (e.g., sinusoidal) for optimally driving theultrasonic transducer.

At block 2220 of the pre-distortion algorithm, the current through themotional branch of the ultrasonic transducer is determined. The motionalbranch current may be determined using Kirchhoff's Current Law based on,for example, the current and voltage feedback samples stored at memorylocation 2180 (which, when suitably scaled, may be representative ofI_(g) and V_(g) in the model of FIG. 25 discussed above), a value of theultrasonic transducer static capacitance C₀ (measured or known a priori)and a known value of the drive frequency. A motional branch currentsample for each set of stored current and voltage feedback samplesassociated with a LUT sample may be determined.

At block 2240 of the pre-distortion algorithm, each motional branchcurrent sample determined at block 2220 is compared to a sample of adesired current waveform shape to determine a difference, or sampleamplitude error, between the compared samples. For this determination,the sample of the desired current waveform shape may be supplied, forexample, from a waveform shape LUT 2260 containing amplitude samples forone cycle of a desired current waveform shape. The particular sample ofthe desired current waveform shape from the LUT 2260 used for thecomparison may be dictated by the LUT sample address associated with themotional branch current sample used in the comparison. Accordingly, theinput of the motional branch current to block 2240 may be synchronizedwith the input of its associated LUT sample address to block 2240. TheLUT samples stored in the programmable logic device 1660 and the LUTsamples stored in the waveform shape LUT 2260 may therefore be equal innumber. In certain aspects, the desired current waveform shaperepresented by the LUT samples stored in the waveform shape LUT 2260 maybe a fundamental sine wave. Other waveform shapes may be desirable. Forexample, it is contemplated that a fundamental sine wave for drivingmain longitudinal motion of an ultrasonic transducer superimposed withone or more other drive signals at other frequencies, such as a thirdorder harmonic for driving at least two mechanical resonances forbeneficial vibrations of transverse or other modes, could be used.

Each value of the sample amplitude error determined at block 2240 may betransmitted to the LUT of the programmable logic device 1660 (shown atblock 2280 in FIG. 28A) along with an indication of its associated LUTaddress. Based on the value of the sample amplitude error and itsassociated address (and, optionally, values of sample amplitude errorfor the same LUT address previously received), the LUT 2280 (or othercontrol block of the programmable logic device 1660) may pre-distort ormodify the value of the LUT sample stored at the LUT address such thatthe sample amplitude error is reduced or minimized. It will beappreciated that such pre-distortion or modification of each LUT samplein an iterative manner across the entire range of LUT addresses willcause the waveform shape of the generator's output current to match orconform to the desired current waveform shape represented by the samplesof the waveform shape LUT 2260.

Current and voltage amplitude measurements, power measurements andimpedance measurements may be determined at block 2300 of the processor1740 based on the current and voltage feedback samples stored at memorylocation 2180. Prior to the determination of these quantities, thefeedback samples may be suitably scaled and, in certain aspects,processed through a suitable filter 2320 to remove noise resulting from,for example, the data acquisition process and induced harmoniccomponents. The filtered voltage and current samples may thereforesubstantially represent the fundamental frequency of the generator'sdrive output signal. In certain aspects, the filter 2320 may be a finiteimpulse response (FIR) filter applied in the frequency domain. Suchaspects may use the Fast Fourier Transform (FFT) of the output drivesignal current and voltage signals. In certain aspects, the resultingfrequency spectrum may be used to provide additional generatorfunctionality. In one aspect, for example, the ratio of the secondand/or third order harmonic component relative to the fundamentalfrequency component may be used as a diagnostic indicator.

At block 2340 (FIG. 28B), a root mean square (RMS) calculation may beapplied to a sample size of the current feedback samples representing anintegral number of cycles of the drive signal to generate a measurementI_(rms) representing the drive signal output current.

At block 2360, a root mean square (RMS) calculation may be applied to asample size of the voltage feedback samples representing an integralnumber of cycles of the drive signal to determine a measurement V_(rms)representing the drive signal output voltage.

At block 2380, the current and voltage feedback samples may bemultiplied point by point, and a mean calculation is applied to samplesrepresenting an integral number of cycles of the drive signal todetermine a measurement P_(r) of the generator's real output power.

At block 2400, measurement P_(a) of the generator's apparent outputpower may be determined as the product V_(rms)/I_(rms).

At block 2420, measurement Z_(m) of the load impedance magnitude may bedetermined as the quotient V_(rms)/I_(rms).

In certain aspects, the quantities I_(rms), V_(rms), P_(r), P_(a) andZ_(m) determined at blocks 2340, 2360, 2380, 2400 and 2420 may be usedby the generator 1100 to implement any of a number of control and/ordiagnostic processes. In certain aspects, any of these quantities may becommunicated to a user via, for example, an output device 2140 integralwith the generator 1100 or an output device 2140 connected to thegenerator 1100 through a suitable communication interface (e.g., a USBinterface). Various diagnostic processes may include, withoutlimitation, handpiece integrity, instrument integrity, instrumentattachment integrity, instrument overload, approaching instrumentoverload, frequency lock failure, over-voltage condition, over-currentcondition, over-power condition, voltage sense failure, current sensefailure, audio indication failure, visual indication failure, shortcircuit condition, power delivery failure, or blocking capacitorfailure, for example.

Block 2440 of the processor 1740 may implement a phase control algorithmfor determining and controlling the impedance phase of an electricalload (e.g., the ultrasonic transducer) driven by the generator 1100. Asdiscussed above, by controlling the frequency of the drive signal tominimize or reduce the difference between the determined impedance phaseand an impedance phase setpoint (e.g., 0°), the effects of harmonicdistortion may be minimized or reduced, and the accuracy of the phasemeasurement increased.

The phase control algorithm receives as input the current and voltagefeedback samples stored in the memory location 2180. Prior to their usein the phase control algorithm, the feedback samples may be suitablyscaled and, in certain aspects, processed through a suitable filter 2460(which may be identical to filter 2320) to remove noise resulting fromthe data acquisition process and induced harmonic components, forexample. The filtered voltage and current samples may thereforesubstantially represent the fundamental frequency of the generator'sdrive output signal.

At block 2480 of the phase control algorithm, the current through themotional branch of the ultrasonic transducer is determined. Thisdetermination may be identical to that described above in connectionwith block 2220 of the pre-distortion algorithm. The output of block2480 may thus be, for each set of stored current and voltage feedbacksamples associated with a LUT sample, a motional branch current sample.

At block 2500 of the phase control algorithm, impedance phase isdetermined based on the synchronized input of motional branch currentsamples determined at block 2480 and corresponding voltage feedbacksamples. In certain aspects, the impedance phase is determined as theaverage of the impedance phase measured at the rising edge of thewaveforms and the impedance phase measured at the falling edge of thewaveforms.

At block 2520 of the of the phase control algorithm, the value of theimpedance phase determined at block 2220 is compared to phase setpoint2540 to determine a difference, or phase error, between the comparedvalues.

At block 2560 (FIG. 28A) of the phase control algorithm, based on avalue of phase error determined at block 2520 and the impedancemagnitude determined at block 2420, a frequency output for controllingthe frequency of the drive signal is determined. The value of thefrequency output may be continuously adjusted by the block 2560 andtransferred to a DDS control block 2680 (discussed below) in order tomaintain the impedance phase determined at block 2500 at the phasesetpoint (e.g., zero phase error). In certain aspects, the impedancephase may be regulated to a 0° phase setpoint. In this way, any harmonicdistortion will be centered about the crest of the voltage waveform,enhancing the accuracy of phase impedance determination.

Block 2580 of the processor 1740 may implement an algorithm formodulating the current amplitude of the drive signal in order to controlthe drive signal current, voltage and power in accordance with userspecified setpoints, or in accordance with requirements specified byother processes or algorithms implemented by the generator 1100. Controlof these quantities may be realized, for example, by scaling the LUTsamples in the LUT 2280 and/or by adjusting the full-scale outputvoltage of the DAC 1680 (which supplies the input to the power amplifier1620) via a DAC 1860. Block 2600 (which may be implemented as a PIDcontroller in certain aspects) may receive, as input, current feedbacksamples (which may be suitably scaled and filtered) from the memorylocation 2180. The current feedback samples may be compared to a“current demand” I_(d) value dictated by the controlled variable (e.g.,current, voltage or power) to determine if the drive signal is supplyingthe necessary current. In aspects in which drive signal current is thecontrol variable, the current demand I_(d) may be specified directly bya current setpoint 2620A (I_(sp)). For example, an RMS value of thecurrent feedback data (determined as in block 2340) may be compared touser-specified RMS current setpoint l_(sp) to determine the appropriatecontroller action. If, for example, the current feedback data indicatesan RMS value less than the current setpoint I_(sp), LUT scaling and/orthe full-scale output voltage of the DAC 1680 may be adjusted by theblock 2600 such that the drive signal current is increased. Conversely,block 2600 may adjust LUT scaling and/or the full-scale output voltageof the DAC 1680 to decrease the drive signal current when the currentfeedback data indicates an RMS value greater than the current setpointI_(sp).

In aspects in which the drive signal voltage is the control variable,the current demand I_(d) may be specified indirectly, for example, basedon the current required to maintain a desired voltage setpoint 2620B(V_(sp)) given the load impedance magnitude Z_(m) measured at block 2420(e.g. I_(d)=V_(sp)/Z_(m)). Similarly, in aspects in which drive signalpower is the control variable, the current demand I_(d) may be specifiedindirectly, for example, based on the current required to maintain adesired power setpoint 2620C (P_(sp)) given the voltage V_(rms) measuredat blocks 2360 (e.g. I_(d)=P_(sp)/V_(rms)).

Block 2680 (FIG. 28A) may implement a DDS control algorithm forcontrolling the drive signal by recalling LUT samples stored in the LUT2280. In certain aspects, the DDS control algorithm may be anumerically-controlled oscillator (NCO) algorithm for generating samplesof a waveform at a fixed clock rate using a point (memorylocation)-skipping technique. The NCO algorithm may implement a phaseaccumulator, or frequency-to-phase converter, that functions as anaddress pointer for recalling LUT samples from the LUT 2280. In oneaspect, the phase accumulator may be a D step size, modulo N phaseaccumulator, where D is a positive integer representing a frequencycontrol value, and N is the number of LUT samples in the LUT 2280. Afrequency control value of D=1, for example, may cause the phaseaccumulator to sequentially point to every address of the LUT 2280,resulting in a waveform output replicating the waveform stored in theLUT 2280. When D>1, the phase accumulator may skip addresses in the LUT2280, resulting in a waveform output having a higher frequency.Accordingly, the frequency of the waveform generated by the DDS controlalgorithm may therefore be controlled by suitably varying the frequencycontrol value. In certain aspects, the frequency control value may bedetermined based on the output of the phase control algorithmimplemented at block 2440. The output of block 2680 may supply the inputof DAC 1680, which in turn supplies a corresponding analog signal to aninput of the power amplifier 1620.

Block 2700 of the processor 1740 may implement a switch-mode convertercontrol algorithm for dynamically modulating the rail voltage of thepower amplifier 1620 based on the waveform envelope of the signal beingamplified, thereby improving the efficiency of the power amplifier 1620.In certain aspects, characteristics of the waveform envelope may bedetermined by monitoring one or more signals contained in the poweramplifier 1620. In one aspect, for example, characteristics of thewaveform envelope may be determined by monitoring the minima of a drainvoltage (e.g., a MOSFET drain voltage) that is modulated in accordancewith the envelope of the amplified signal. A minima voltage signal maybe generated, for example, by a voltage minima detector coupled to thedrain voltage. The minima voltage signal may be sampled by ADC 1760,with the output minima voltage samples being received at block 2720 ofthe switch-mode converter control algorithm. Based on the values of theminima voltage samples, block 2740 may control a PWM signal output by aPWM generator 2760, which, in turn, controls the rail voltage suppliedto the power amplifier 1620 by the switch-mode regulator 1700. Incertain aspects, as long as the values of the minima voltage samples areless than a minima target 2780 input into block 2720, the rail voltagemay be modulated in accordance with the waveform envelope ascharacterized by the minima voltage samples. When the minima voltagesamples indicate low envelope power levels, for example, block 2740 maycause a low rail voltage to be supplied to the power amplifier 1620,with the full rail voltage being supplied only when the minima voltagesamples indicate maximum envelope power levels. When the minima voltagesamples fall below the minima target 2780, block 2740 may cause the railvoltage to be maintained at a minimum value suitable for ensuring properoperation of the power amplifier 1620.

FIG. 29 is a schematic diagram of one aspect of an electrical circuit2900, suitable for driving an ultrasonic transducer, such as ultrasonictransducer 1120, in accordance with at least one aspect of the presentdisclosure. The electrical circuit 2900 comprises an analog multiplexer2980. The analog multiplexer 2980 multiplexes various signals from theupstream channels SCL-A, SDA-A such as ultrasonic, battery, and powercontrol circuit. A current sensor 2982 is coupled in series with thereturn or ground leg of the power supply circuit to measure the currentsupplied by the power supply. A field effect transistor (FET)temperature sensor 2984 provides the ambient temperature. A pulse widthmodulation (PWM) watchdog timer 2988 automatically generates a systemreset if the main program neglects to periodically service it. It isprovided to automatically reset the electrical circuit 2900 when ithangs or freezes because of a software or hardware fault. It will beappreciated that the electrical circuit 2900 may be configured as an RFdriver circuit for driving the ultrasonic transducer or for driving RFelectrodes such as the electrical circuit 3600 shown in FIG. 34, forexample. Accordingly, with reference now back to FIG. 29, the electricalcircuit 2900 can be used to drive both ultrasonic transducers and RFelectrodes interchangeably. If driven simultaneously, filter circuitsmay be provided in the corresponding first stage circuits 3404 (FIG. 32)to select either the ultrasonic waveform or the RF waveform. Suchfiltering techniques are described in commonly owned U.S. Pat. Pub. No.US-2017-0086910-A1, titled TECHNIQUES FOR CIRCUIT TOPOLOGIES FORCOMBINED GENERATOR, which is herein incorporated by reference in itsentirety.

A drive circuit 2986 provides left and right ultrasonic energy outputs.A digital signal that represents the signal waveform is provided to theSCL-A, SDA-A inputs of the analog multiplexer 2980 from a controlcircuit, such as the control circuit 3200 (FIG. 30). A digital-to-analogconverter 2990 (DAC) converts the digital input to an analog output todrive a PWM circuit 2992 coupled to an oscillator 2994. The PWM circuit2992 provides a first signal to a first gate drive circuit 2996 acoupled to a first transistor output stage 2998 a to drive a firstUltrasonic (LEFT) energy output. The PWM circuit 2992 also provides asecond signal to a second gate drive circuit 2996 b coupled to a secondtransistor output stage 2998 b to drive a second Ultrasonic (RIGHT)energy output. A voltage sensor 2999 is coupled between the UltrasonicLEFT/RIGHT output terminals to measure the output voltage. The drivecircuit 2986, the first and second drive circuits 2996 a, 2996 b, andthe first and second transistor output stages 2998 a, 2998 b define afirst stage amplifier circuit. In operation, the control circuit 3200(FIG. 30) generates a digital waveform 4300 (FIG. 37) employing circuitssuch as direct digital synthesis (DDS) circuits 4100, 4200 (FIGS. 35 and36). The DAC 2990 receives the digital waveform 4300 and converts itinto an analog waveform, which is received and amplified by the firststage amplifier circuit.

FIG. 30 is a schematic diagram of a control circuit 3200, such ascontrol circuit 3212, in accordance with at least one aspect of thepresent disclosure. The control circuit 3200 is located within a housingof the battery assembly. The battery assembly is the energy source for avariety of local power supplies 3215. The control circuit comprises amain processor 3214 coupled via an interface master 3218 to variousdownstream circuits by way of outputs SCL-A and SDA-A, SCL-B and SDA-B,SCL-C and SDA-C, for example. In one aspect, the interface master 3218is a general purpose serial interface such as an I²C serial interface.The main processor 3214 also is configured to drive switches 3224through general purposes input/output (GPIO) 3220, a display 3226 (e.g.,and LCD display), and various indicators 3228 through GPIO 3222. Awatchdog processor 3216 is provided to control the main processor 3214.A switch 3230 is provided in series with a battery 3211 to activate thecontrol circuit 3212 upon insertion of the battery assembly into ahandle assembly of a surgical instrument.

In one aspect, the main processor 3214 is coupled to the electricalcircuit 2900 (FIG. 29) by way of output terminals SCL-A, SDA-A. The mainprocessor 3214 comprises a memory for storing tables of digitized drivesignals or waveforms that are transmitted to the electrical circuit 2900for driving the ultrasonic transducer 1120, for example. In otheraspects, the main processor 3214 may generate a digital waveform andtransmit it to the electrical circuit 2900 or may store the digitalwaveform for later transmission to the electrical circuit 2900. The mainprocessor 3214 also may provide RF drive by way of output terminalsSCL-B, SDA-B and various sensors (e.g., Hall-effect sensors,magneto-rheological fluid (MRF) sensors, etc.) by way of outputterminals SCL-C, SDA-C. In one aspect, the main processor 3214 isconfigured to sense the presence of ultrasonic drive circuitry and/or RFdrive circuitry to enable appropriate software and user interfacefunctionality.

In one aspect, the main processor 3214 may be an LM 4F230H5QR, availablefrom Texas Instruments, for example. In at least one example, the TexasInstruments LM4F230H5QR is an ARM Cortex-M4F Processor Core comprisingon-chip memory of 256 KB single-cycle flash memory, or othernon-volatile memory, up to 40 MHz, a prefetch buffer to improveperformance above 40 MHz, a 32 KB single-cycle serial random accessmemory (SRAM), internal read-only memory (ROM) loaded withStellarisWare® software, 2 KB electrically erasable programmableread-only memory (EEPROM), one or more pulse width modulation (PWM)modules, one or more quadrature encoder inputs (QED analog, one or more12-bit Analog-to-Digital Converters (ADC) with 12 analog input channels,among other features that are readily available from the productdatasheet. Other processors may be readily substituted and, accordingly,the present disclosure should not be limited in this context.

FIG. 31 shows a simplified block circuit diagram illustrating anotherelectrical circuit 3300 contained within a modular ultrasonic surgicalinstrument 3334, in accordance with at least one aspect of the presentdisclosure. The electrical circuit 3300 includes a processor 3302, aclock 3330, a memory 3326, a power supply 3304 (e.g., a battery), aswitch 3306, such as a metal-oxide semiconductor field effect transistor(MOSFET) power switch, a drive circuit 3308 (PLL), a transformer 3310, asignal smoothing circuit 3312 (also referred to as a matching circuitand can be, for example, a tank circuit), a sensing circuit 3314, atransducer 1120, and a shaft assembly (e.g. shaft assembly 1126, 1129)comprising an ultrasonic transmission waveguide that terminates at anultrasonic blade (e.g. ultrasonic blade 1128, 1149) which may bereferred to herein simply as the waveguide.

One feature of the present disclosure that severs dependency on highvoltage (120 VAC) input power (a characteristic of general ultrasoniccutting devices) is the utilization of low-voltage switching throughoutthe wave-forming process and the amplification of the driving signalonly directly before the transformer stage. For this reason, in oneaspect of the present disclosure, power is derived from only a battery,or a group of batteries, small enough to fit either within a handleassembly. State-of-the-art battery technology provides powerfulbatteries of a few centimeters in height and width and a few millimetersin depth. By combining the features of the present disclosure to providea self-contained and self-powered ultrasonic device, a reduction inmanufacturing cost may be achieved.

The output of the power supply 3304 is fed to and powers the processor3302. The processor 3302 receives and outputs signals and, as will bedescribed below, functions according to custom logic or in accordancewith computer programs that are executed by the processor 3302. Asdiscussed above, the electrical circuit 3300 can also include a memory3326, preferably, random access memory (RAM), that storescomputer-readable instructions and data.

The output of the power supply 3304 also is directed to the switch 3306having a duty cycle controlled by the processor 3302. By controlling theon-time for the switch 3306, the processor 3302 is able to dictate thetotal amount of power that is ultimately delivered to the transducer1120. In one aspect, the switch 3306 is a MOSFET, although otherswitches and switching configurations are adaptable as well. The outputof the switch 3306 is fed to a drive circuit 3308 that contains, forexample, a phase detecting phase-locked loop (PLL) and/or a low-passfilter and/or a voltage-controlled oscillator. The output of the switch3306 is sampled by the processor 3302 to determine the voltage andcurrent of the output signal (V_(IN) and I_(IN), respectively). Thesevalues are used in a feedback architecture to adjust the pulse widthmodulation of the switch 3306. For instance, the duty cycle of theswitch 3306 can vary from about 20% to about 80%, depending on thedesired and actual output from the switch 3306.

The drive circuit 3308, which receives the signal from the switch 3306,includes an oscillatory circuit that turns the output of the switch 3306into an electrical signal having an ultrasonic frequency, e.g., 55 kHz(VCO). As explained above, a smoothed-out version of this ultrasonicwaveform is ultimately fed to the ultrasonic transducer 1120 to producea resonant sine wave along an ultrasonic transmission waveguide.

At the output of the drive circuit 3308 is a transformer 3310 that isable to step up the low voltage signal(s) to a higher voltage. It isnoted that upstream switching, prior to the transformer 3310, isperformed at low (e.g., battery driven) voltages, something that, todate, has not been possible for ultrasonic cutting and cautery devices.This is at least partially due to the fact that the deviceadvantageously uses low on-resistance MOSFET switching devices. Lowon-resistance MOSFET switches are advantageous, as they produce lowerswitching losses and less heat than a traditional MOSFET device andallow higher current to pass through. Therefore, the switching stage(pre-transformer) can be characterized as low voltage/high current. Toensure the lower on-resistance of the amplifier MOSFET(s), the MOSFET(s)are run, for example, at 10 V. In such a case, a separate 10 VDC powersupply can be used to feed the MOSFET gate, which ensures that theMOSFET is fully on and a reasonably low on resistance is achieved. Inone aspect of the present disclosure, the transformer 3310 steps up thebattery voltage to 120 V root-mean-square (RMS). Transformers are knownin the art and are, therefore, not explained here in detail.

In the circuit configurations described, circuit component degradationcan negatively impact the circuit performance of the circuit. One factorthat directly affects component performance is heat. Known circuitsgenerally monitor switching temperatures (e.g., MOSFET temperatures).However, because of the technological advancements in MOSFET designs,and the corresponding reduction in size, MOSFET temperatures are nolonger a valid indicator of circuit loads and heat. For this reason, inaccordance with at least one aspect of the present disclosure, thesensing circuit 3314 senses the temperature of the transformer 3310.This temperature sensing is advantageous as the transformer 3310 is runat or very close to its maximum temperature during use of the device.Additional temperature will cause the core material, e.g., the ferrite,to break down and permanent damage can occur. The present disclosure canrespond to a maximum temperature of the transformer 3310 by, forexample, reducing the driving power in the transformer 3310, signalingthe user, turning the power off, pulsing the power, or other appropriateresponses.

In one aspect of the present disclosure, the processor 3302 iscommunicatively coupled to the end effector (e.g. 1122, 1125), which isused to place material in physical contact with the ultrasonic blade(e.g. 1128, 1149). Sensors are provided that measure, at the endeffector, a clamping force value (existing within a known range) and,based upon the received clamping force value, the processor 3302 variesthe motional voltage V_(M). Because high force values combined with aset motional rate can result in high blade temperatures, a temperaturesensor 3332 can be communicatively coupled to the processor 3302, wherethe processor 3302 is operable to receive and interpret a signalindicating a current temperature of the blade from the temperaturesensor 3336 and to determine a target frequency of blade movement basedupon the received temperature. In another aspect, force sensors such asstrain gages or pressure sensors may be coupled to the trigger (e.g.1143, 1147) to measure the force applied to the trigger by the user. Inanother aspect, force sensors such as strain gages or pressure sensorsmay be coupled to a switch button such that displacement intensitycorresponds to the force applied by the user to the switch button.

In accordance with at least one aspect of the present disclosure, thePLL portion of the drive circuit 3308, which is coupled to the processor3302, is able to determine a frequency of waveguide movement andcommunicate that frequency to the processor 3302. The processor 3302stores this frequency value in the memory 3326 when the device is turnedoff. By reading the clock 3330, the processor 3302 is able to determinean elapsed time after the device is shut off and retrieve the lastfrequency of waveguide movement if the elapsed time is less than apredetermined value. The device can then start up at the last frequency,which, presumably, is the optimum frequency for the current load.

Modular Battery Powered Handheld Surgical Instrument with MultistageGenerator Circuits

In another aspect, the present disclosure provides a modular batterypowered handheld surgical instrument with multistage generator circuits.Disclosed is a surgical instrument that includes a battery assembly, ahandle assembly, and a shaft assembly where the battery assembly and theshaft assembly are configured to mechanically and electrically connectto the handle assembly. The battery assembly includes a control circuitconfigured to generate a digital waveform. The handle assembly includesa first stage circuit configured to receive the digital waveform,convert the digital waveform into an analog waveform, and amplify theanalog waveform. The shaft assembly includes a second stage circuitcoupled to the first stage circuit to receive, amplify, and apply theanalog waveform to a load.

In one aspect, the present disclosure provides a surgical instrument,comprising: a battery assembly, comprising a control circuit comprisinga battery, a memory coupled to the battery, and a processor coupled tothe memory and the battery, wherein the processor is configured togenerate a digital waveform; a handle assembly comprising a first stagecircuit coupled to the processor, the first stage circuit comprising adigital-to-analog (DAC) converter and a first stage amplifier circuit,wherein the DAC is configured to receive the digital waveform andconvert the digital waveform into an analog waveform, wherein the firststage amplifier circuit is configured to receive and amplify the analogwaveform; and a shaft assembly comprising a second stage circuit coupledto the first stage amplifier circuit to receive the analog waveform,amplify the analog waveform, and apply the analog waveform to a load;wherein the battery assembly and the shaft assembly are configured tomechanically and electrically connect to the handle assembly.

The load may comprise any one of an ultrasonic transducer, an electrode,or a sensor, or any combinations thereof. The first stage circuit maycomprise a first stage ultrasonic drive circuit and a first stagehigh-frequency current drive circuit. The control circuit may beconfigured to drive the first stage ultrasonic drive circuit and thefirst stage high-frequency current drive circuit independently orsimultaneously. The first stage ultrasonic drive circuit may beconfigured to couple to a second stage ultrasonic drive circuit. Thesecond stage ultrasonic drive circuit may be configured to couple to anultrasonic transducer. The first stage high-frequency current drivecircuit may be configured to couple to a second stage high-frequencydrive circuit. The second stage high-frequency drive circuit may beconfigured to couple to an electrode.

The first stage circuit may comprise a first stage sensor drive circuit.The first stage sensor drive circuit may be configured to a second stagesensor drive circuit. The second stage sensor drive circuit may beconfigured to couple to a sensor.

In another aspect, the present disclosure provides a surgicalinstrument, comprising: a battery assembly, comprising a control circuitcomprising a battery, a memory coupled to the battery, and a processorcoupled to the memory and the battery, wherein the processor isconfigured to generate a digital waveform; a handle assembly comprisinga common first stage circuit coupled to the processor, the common firststage circuit comprising a digital-to-analog (DAC) converter and acommon first stage amplifier circuit, wherein the DAC is configured toreceive the digital waveform and convert the digital waveform into ananalog waveform, wherein the common first stage amplifier circuit isconfigured to receive and amplify the analog waveform; and a shaftassembly comprising a second stage circuit coupled to the common firststage amplifier circuit to receive the analog waveform, amplify theanalog waveform, and apply the analog waveform to a load; wherein thebattery assembly and the shaft assembly are configured to mechanicallyand electrically connect to the handle assembly.

The load may comprise any one of an ultrasonic transducer, an electrode,or a sensor, or any combinations thereof. The common first stage circuitmay be configured to drive ultrasonic, high-frequency current, or sensorcircuits. The common first stage drive circuit may be configured tocouple to a second stage ultrasonic drive circuit, a second stagehigh-frequency drive circuit, or a second stage sensor drive circuit.The second stage ultrasonic drive circuit may be configured to couple toan ultrasonic transducer, the second stage high-frequency drive circuitis configured to couple to an electrode, and the second stage sensordrive circuit is configured to couple to a sensor.

In another aspect, the present disclosure provides a surgicalinstrument, comprising a control circuit comprising a memory coupled toa processor, wherein the processor is configured to generate a digitalwaveform; a handle assembly comprising a common first stage circuitcoupled to the processor, the common first stage circuit configured toreceive the digital waveform, convert the digital waveform into ananalog waveform, and amplify the analog waveform; and a shaft assemblycomprising a second stage circuit coupled to the common first stagecircuit to receive and amplify the analog waveform; wherein the shaftassembly is configured to mechanically and electrically connect to thehandle assembly.

The common first stage circuit may be configured to drive ultrasonic,high-frequency current, or sensor circuits. The common first stage drivecircuit may be configured to couple to a second stage ultrasonic drivecircuit, a second stage high-frequency drive circuit, or a second stagesensor drive circuit. The second stage ultrasonic drive circuit may beconfigured to couple to an ultrasonic transducer, the second stagehigh-frequency drive circuit is configured to couple to an electrode,and the second stage sensor drive circuit is configured to couple to asensor.

FIG. 32 illustrates a generator circuit 3400 partitioned into a firststage circuit 3404 and a second stage circuit 3406, in accordance withat least one aspect of the present disclosure. In one aspect, thesurgical instruments of surgical system 1000 described herein maycomprise a generator circuit 3400 partitioned into multiple stages. Forexample, surgical instruments of surgical system 1000 may comprise thegenerator circuit 3400 partitioned into at least two circuits: the firststage circuit 3404 and the second stage circuit 3406 of amplificationenabling operation of RF energy only, ultrasonic energy only, and/or acombination of RF energy and ultrasonic energy. A combination modularshaft assembly 3414 may be powered by the common first stage circuit3404 located within a handle assembly 3412 and the modular second stagecircuit 3406 integral to the modular shaft assembly 3414. As previouslydiscussed throughout this description in connection with the surgicalinstruments of surgical system 1000, a battery assembly 3410 and theshaft assembly 3414 are configured to mechanically and electricallyconnect to the handle assembly 3412. The end effector assembly isconfigured to mechanically and electrically connect the shaft assembly3414.

Turning now to FIG. 32, the generator circuit 3400 is partitioned intomultiple stages located in multiple modular assemblies of a surgicalinstrument, such as the surgical instruments of surgical system 1000described herein. In one aspect, a control stage circuit 3402 may belocated in the battery assembly 3410 of the surgical instrument. Thecontrol stage circuit 3402 is a control circuit 3200 as described inconnection with FIG. 30. The control circuit 3200 comprises a processor3214, which includes internal memory 3217 (FIG. 32) (e.g., volatile andnon-volatile memory), and is electrically coupled to a battery 3211. Thebattery 3211 supplies power to the first stage circuit 3404, the secondstage circuit 3406, and a third stage circuit 3408, respectively. Aspreviously discussed, the control circuit 3200 generates a digitalwaveform 4300 (FIG. 37) using circuits and techniques described inconnection with FIGS. 35 and 36. Returning to FIG. 32, the digitalwaveform 4300 may be configured to drive an ultrasonic transducer,high-frequency (e.g., RF) electrodes, or a combination thereof eitherindependently or simultaneously. If driven simultaneously, filtercircuits may be provided in the corresponding first stage circuits 3404to select either the ultrasonic waveform or the RF waveform. Suchfiltering techniques are described in commonly owned U.S. Pat. Pub. No.US-2017-0086910-A1, titled TECHNIQUES FOR CIRCUIT TOPOLOGIES FORCOMBINED GENERATOR, which is herein incorporated by reference in itsentirety.

The first stage circuits 3404 (e.g., the first stage ultrasonic drivecircuit 3420, the first stage RF drive circuit 3422, and the first stagesensor drive circuit 3424) are located in a handle assembly 3412 of thesurgical instrument. The control circuit 3200 provides the ultrasonicdrive signal to the first stage ultrasonic drive circuit 3420 viaoutputs SCL-A, SDA-A of the control circuit 3200. The first stageultrasonic drive circuit 3420 is described in detail in connection withFIG. 29. The control circuit 3200 provides the RF drive signal to thefirst stage RF drive circuit 3422 via outputs SCL-B, SDA-B of thecontrol circuit 3200. The first stage RF drive circuit 3422 is describedin detail in connection with FIG. 34. The control circuit 3200 providesthe sensor drive signal to the first stage sensor drive circuit 3424 viaoutputs SCL-C, SDA-C of the control circuit 3200. Generally, each of thefirst stage circuits 3404 includes a digital-to-analog (DAC) converterand a first stage amplifier section to drive the second stage circuits3406. The outputs of the first stage circuits 3404 are provided to theinputs of the second stage circuits 3406.

The control circuit 3200 is configured to detect which modules areplugged into the control circuit 3200. For example, the control circuit3200 is configured to detect whether the first stage ultrasonic drivecircuit 3420, the first stage RF drive circuit 3422, or the first stagesensor drive circuit 3424 located in the handle assembly 3412 isconnected to the battery assembly 3410. Likewise, each of the firststage circuits 3404 can detect which second stage circuits 3406 areconnected thereto and that information is provided back to the controlcircuit 3200 to determine the type of signal waveform to generate.Similarly, each of the second stage circuits 3406 can detect which thirdstage circuits 3408 or components are connected thereto and thatinformation is provided back to the control circuit 3200 to determinethe type of signal waveform to generate.

In one aspect, the second stage circuits 3406 (e.g., the ultrasonicdrive second stage circuit 3430, the RF drive second stage circuit 3432,and the sensor drive second stage circuit 3434) are located in the shaftassembly 3414 of the surgical instrument. The first stage ultrasonicdrive circuit 3420 provides a signal to the second stage ultrasonicdrive circuit 3430 via outputs US-Left/US-Right. The second stageultrasonic drive circuit 3430 can include, for example, a transformer,filter, amplifier, and/or signal conditioning circuits. The first stagehigh-frequency (RF) current drive circuit 3422 provides a signal to thesecond stage RF drive circuit 3432 via outputs RF-Left/RF-Right. Inaddition to a transformer and blocking capacitors, the second stage RFdrive circuit 3432 also may include filter, amplifier, and signalconditioning circuits. The first stage sensor drive circuit 3424provides a signal to the second stage sensor drive circuit 3434 viaoutputs Sensor-1/Sensor-2. The second stage sensor drive circuit 3434may include filter, amplifier, and signal conditioning circuitsdepending on the type of sensor. The outputs of the second stagecircuits 3406 are provided to the inputs of the third stage circuits3408.

In one aspect, the third stage circuits 3408 (e.g., the ultrasonictransducer 1120, the RF electrodes 3074 a, 3074 b, and the sensors 3440)may be located in various assemblies 3416 of the surgical instruments.In one aspect, the second stage ultrasonic drive circuit 3430 provides adrive signal to the ultrasonic transducer 1120 piezoelectric stack. Inone aspect, the ultrasonic transducer 1120 is located in the ultrasonictransducer assembly of the surgical instrument. In other aspects,however, the ultrasonic transducer 1120 may be located in the handleassembly 3412, the shaft assembly 3414, or the end effector. In oneaspect, the second stage RF drive circuit 3432 provides a drive signalto the RF electrodes 3074 a, 3074 b, which are generally located in theend effector portion of the surgical instrument. In one aspect, thesecond stage sensor drive circuit 3434 provides a drive signal tovarious sensors 3440 located throughout the surgical instrument.

FIG. 33 illustrates a generator circuit 3500 partitioned into multiplestages where a first stage circuit 3504 is common to the second stagecircuit 3506, in accordance with at least one aspect of the presentdisclosure. In one aspect, the surgical instruments of surgical system1000 described herein may comprise generator circuit 3500 partitionedinto multiple stages. For example, the surgical instruments of surgicalsystem 1000 may comprise the generator circuit 3500 partitioned into atleast two circuits: the first stage circuit 3504 and the second stagecircuit 3506 of amplification enabling operation of high-frequency (RF)energy only, ultrasonic energy only, and/or a combination of RF energyand ultrasonic energy. A combination modular shaft assembly 3514 may bepowered by a common first stage circuit 3504 located within the handleassembly 3512 and a modular second stage circuit 3506 integral to themodular shaft assembly 3514. As previously discussed throughout thisdescription in connection with the surgical instruments of surgicalsystem 1000, a battery assembly 3510 and the shaft assembly 3514 areconfigured to mechanically and electrically connect to the handleassembly 3512. The end effector assembly is configured to mechanicallyand electrically connect the shaft assembly 3514.

As shown in the example of FIG. 33, the battery assembly 3510 portion ofthe surgical instrument comprises a first control circuit 3502, whichincludes the control circuit 3200 previously described. The handleassembly 3512, which connects to the battery assembly 3510, comprises acommon first stage drive circuit 3420. As previously discussed, thefirst stage drive circuit 3420 is configured to drive ultrasonic,high-frequency (RF) current, and sensor loads. The output of the commonfirst stage drive circuit 3420 can drive any one of the second stagecircuits 3506 such as the second stage ultrasonic drive circuit 3430,the second stage high-frequency (RF) current drive circuit 3432, and/orthe second stage sensor drive circuit 3434. The common first stage drivecircuit 3420 detects which second stage circuit 3506 is located in theshaft assembly 3514 when the shaft assembly 3514 is connected to thehandle assembly 3512. Upon the shaft assembly 3514 being connected tothe handle assembly 3512, the common first stage drive circuit 3420determines which one of the second stage circuits 3506 (e.g., the secondstage ultrasonic drive circuit 3430, the second stage RF drive circuit3432, and/or the second stage sensor drive circuit 3434) is located inthe shaft assembly 3514. The information is provided to the controlcircuit 3200 located in the handle assembly 3512 in order to supply asuitable digital waveform 4300 (FIG. 37) to the second stage circuit3506 to drive the appropriate load, e.g., ultrasonic, RF, or sensor. Itwill be appreciated that identification circuits may be included invarious assemblies 3516 in third stage circuit 3508 such as theultrasonic transducer 1120, the electrodes 3074 a, 3074 b, or thesensors 3440. Thus, when a third stage circuit 3508 is connected to asecond stage circuit 3506, the second stage circuit 3506 knows the typeof load that is required based on the identification information.

FIG. 34 is a schematic diagram of one aspect of an electrical circuit3600 configured to drive a high-frequency current (RF), in accordancewith at least one aspect of the present disclosure. The electricalcircuit 3600 comprises an analog multiplexer 3680. The analogmultiplexer 3680 multiplexes various signals from the upstream channelsSCL-A, SDA-A such as RF, battery, and power control circuit. A currentsensor 3682 is coupled in series with the return or ground leg of thepower supply circuit to measure the current supplied by the powersupply. A field effect transistor (FET) temperature sensor 3684 providesthe ambient temperature. A pulse width modulation (PWM) watchdog timer3688 automatically generates a system reset if the main program neglectsto periodically service it. It is provided to automatically reset theelectrical circuit 3600 when it hangs or freezes because of a softwareor hardware fault. It will be appreciated that the electrical circuit3600 may be configured for driving RF electrodes or for driving theultrasonic transducer 1120 as described in connection with FIG. 29, forexample. Accordingly, with reference now back to FIG. 34, the electricalcircuit 3600 can be used to drive both ultrasonic and RF electrodesinterchangeably.

A drive circuit 3686 provides Left and Right RF energy outputs. Adigital signal that represents the signal waveform is provided to theSCL-A, SDA-A inputs of the analog multiplexer 3680 from a controlcircuit, such as the control circuit 3200 (FIG. 30). A digital-to-analogconverter 3690 (DAC) converts the digital input to an analog output todrive a PWM circuit 3692 coupled to an oscillator 3694. The PWM circuit3692 provides a first signal to a first gate drive circuit 3696 acoupled to a first transistor output stage 3698 a to drive a first RF+(Left) energy output. The PWM circuit 3692 also provides a second signalto a second gate drive circuit 3696 b coupled to a second transistoroutput stage 3698 b to drive a second RF− (Right) energy output. Avoltage sensor 3699 is coupled between the RF Left/RF output terminalsto measure the output voltage. The drive circuit 3686, the first andsecond drive circuits 3696 a, 3696 b, and the first and secondtransistor output stages 3698 a, 3698 b define a first stage amplifiercircuit. In operation, the control circuit 3200 (FIG. 30) generates adigital waveform 4300 (FIG. 37) employing circuits such as directdigital synthesis (DDS) circuits 4100, 4200 (FIGS. 35 and 36). The DAC3690 receives the digital waveform 4300 and converts it into an analogwaveform, which is received and amplified by the first stage amplifiercircuit.

In one aspect, the ultrasonic or high-frequency current generators ofthe surgical system 1000 may be configured to generate the electricalsignal waveform digitally such that the desired using a predeterminednumber of phase points stored in a lookup table to digitize the waveshape. The phase points may be stored in a table defined in a memory, afield programmable gate array (FPGA), or any suitable non-volatilememory. FIG. 35 illustrates one aspect of a fundamental architecture fora digital synthesis circuit such as a direct digital synthesis (DDS)circuit 4100 configured to generate a plurality of wave shapes for theelectrical signal waveform. The generator software and digital controlsmay command the FPGA to scan the addresses in the lookup table 4104which in turn provides varying digital input values to a DAC circuit4108 that feeds a power amplifier. The addresses may be scannedaccording to a frequency of interest. Using such a lookup table 4104enables generating various types of wave shapes that can be fed intotissue or into a transducer, an RF electrode, multiple transducerssimultaneously, multiple RF electrodes simultaneously, or a combinationof RF and ultrasonic instruments. Furthermore, multiple lookup tables4104 that represent multiple wave shapes can be created, stored, andapplied to tissue from a generator.

The waveform signal may be configured to control at least one of anoutput current, an output voltage, or an output power of an ultrasonictransducer and/or an RF electrode, or multiples thereof (e.g. two ormore ultrasonic transducers and/or two or more RF electrodes). Further,where the surgical instrument comprises an ultrasonic components, thewaveform signal may be configured to drive at least two vibration modesof an ultrasonic transducer of the at least one surgical instrument.Accordingly, a generator may be configured to provide a waveform signalto at least one surgical instrument wherein the waveform signalcorresponds to at least one wave shape of a plurality of wave shapes ina table. Further, the waveform signal provided to the two surgicalinstruments may comprise two or more wave shapes. The table may compriseinformation associated with a plurality of wave shapes and the table maybe stored within the generator. In one aspect or example, the table maybe a direct digital synthesis table, which may be stored in an FPGA ofthe generator. The table may be addressed by anyway that is convenientfor categorizing wave shapes. According to one aspect, the table, whichmay be a direct digital synthesis table, is addressed according to afrequency of the waveform signal. Additionally, the informationassociated with the plurality of wave shapes may be stored as digitalinformation in the table.

The analog electrical signal waveform may be configured to control atleast one of an output current, an output voltage, or an output power ofan ultrasonic transducer and/or an RF electrode, or multiples thereof(e.g., two or more ultrasonic transducers and/or two or more RFelectrodes). Further, where the surgical instrument comprises ultrasoniccomponents, the analog electrical signal waveform may be configured todrive at least two vibration modes of an ultrasonic transducer of the atleast one surgical instrument. Accordingly, the generator circuit may beconfigured to provide an analog electrical signal waveform to at leastone surgical instrument wherein the analog electrical signal waveformcorresponds to at least one wave shape of a plurality of wave shapesstored in a lookup table 4104. Further, the analog electrical signalwaveform provided to the two surgical instruments may comprise two ormore wave shapes. The lookup table 4104 may comprise informationassociated with a plurality of wave shapes and the lookup table 4104 maybe stored either within the generator circuit or the surgicalinstrument. In one aspect or example, the lookup table 4104 may be adirect digital synthesis table, which may be stored in an FPGA of thegenerator circuit or the surgical instrument. The lookup table 4104 maybe addressed by anyway that is convenient for categorizing wave shapes.According to one aspect, the lookup table 4104, which may be a directdigital synthesis table, is addressed according to a frequency of thedesired analog electrical signal waveform. Additionally, the informationassociated with the plurality of wave shapes may be stored as digitalinformation in the lookup table 4104.

With the widespread use of digital techniques in instrumentation andcommunications systems, a digitally-controlled method of generatingmultiple frequencies from a reference frequency source has evolved andis referred to as direct digital synthesis. The basic architecture isshown in FIG. 35. In this simplified block diagram, a DDS circuit iscoupled to a processor, controller, or a logic device of the generatorcircuit and to a memory circuit located in the generator circuit of thesurgical system 1000. The DDS circuit 4100 comprises an address counter4102, lookup table 4104, a register 4106, a DAC circuit 4108, and afilter 4112. A stable clock f_(c) is received by the address counter4102 and the register 4106 drives a programmable-read-only-memory (PROM)which stores one or more integral number of cycles of a sinewave (orother arbitrary waveform) in a lookup table 4104. As the address counter4102 steps through memory locations, values stored in the lookup table4104 are written to the register 4106, which is coupled to the DACcircuit 4108. The corresponding digital amplitude of the signal at thememory location of the lookup table 4104 drives the DAC circuit 4108,which in turn generates an analog output signal 4110. The spectralpurity of the analog output signal 4110 is determined primarily by theDAC circuit 4108. The phase noise is basically that of the referenceclock f_(c). The first analog output signal 4110 output from the DACcircuit 4108 is filtered by the filter 4112 and a second analog outputsignal 4114 output by the filter 4112 is provided to an amplifier havingan output coupled to the output of the generator circuit. The secondanalog output signal has a frequency f_(out).

Because the DDS circuit 4100 is a sampled data system, issues involvedin sampling must be considered: quantization noise, aliasing, filtering,etc. For instance, the higher order harmonics of the DAC circuit 4108output frequencies fold back into the Nyquist bandwidth, making themunfilterable, whereas, the higher order harmonics of the output ofphase-locked-loop (PLL) based synthesizers can be filtered. The lookuptable 4104 contains signal data for an integral number of cycles. Thefinal output frequency f_(out) can be changed changing the referenceclock frequency f_(c) or by reprogramming the PROM.

The DDS circuit 4100 may comprise multiple lookup tables 4104 where thelookup table 4104 stores a waveform represented by a predeterminednumber of samples, wherein the samples define a predetermined shape ofthe waveform. Thus multiple waveforms having a unique shape can bestored in multiple lookup tables 4104 to provide different tissuetreatments based on instrument settings or tissue feedback. Examples ofwaveforms include high crest factor RF electrical signal waveforms forsurface tissue coagulation, low crest factor RF electrical signalwaveform for deeper tissue penetration, and electrical signal waveformsthat promote efficient touch-up coagulation. In one aspect, the DDScircuit 4100 can create multiple wave shape lookup tables 4104 andduring a tissue treatment procedure (e.g., “on-the-fly” or in virtualreal time based on user or sensor inputs) switch between different waveshapes stored in separate lookup tables 4104 based on the tissue effectdesired and/or tissue feedback.

Accordingly, switching between wave shapes can be based on tissueimpedance and other factors, for example. In other aspects, the lookuptables 4104 can store electrical signal waveforms shaped to maximize thepower delivered into the tissue per cycle (i.e., trapezoidal or squarewave). In other aspects, the lookup tables 4104 can store wave shapessynchronized in such way that they make maximizing power delivery by themultifunction surgical instrument of surgical system 1000 whiledelivering RF and ultrasonic drive signals. In yet other aspects, thelookup tables 4104 can store electrical signal waveforms to driveultrasonic and RF therapeutic, and/or sub-therapeutic, energysimultaneously while maintaining ultrasonic frequency lock. Custom waveshapes specific to different instruments and their tissue effects can bestored in the non-volatile memory of the generator circuit or in thenon-volatile memory (e.g., EEPROM) of the surgical system 1000 and befetched upon connecting the multifunction surgical instrument to thegenerator circuit. An example of an exponentially damped sinusoid, asused in many high crest factor “coagulation” waveforms is shown in FIG.37.

A more flexible and efficient implementation of the DDS circuit 4100employs a digital circuit called a Numerically Controlled Oscillator(NCO). A block diagram of a more flexible and efficient digitalsynthesis circuit such as a DDS circuit 4200 is shown in FIG. 36. Inthis simplified block diagram, a DDS circuit 4200 is coupled to aprocessor, controller, or a logic device of the generator and to amemory circuit located either in the generator or in any of the surgicalinstruments of surgical system 1000. The DDS circuit 4200 comprises aload register 4202, a parallel delta phase register 4204, an addercircuit 4216, a phase register 4208, a lookup table 4210(phase-to-amplitude converter), a DAC circuit 4212, and a filter 4214.The adder circuit 4216 and the phase register 4208 form part of a phaseaccumulator 4206. A clock frequency f_(c) is applied to the phaseregister 4208 and a DAC circuit 4212. The load register 4202 receives atuning word that specifies output frequency as a fraction of thereference clock frequency signal f_(c). The output of the load register4202 is provided to the parallel delta phase register 4204 with a tuningword M.

The DDS circuit 4200 includes a sample clock that generates the clockfrequency f_(c), the phase accumulator 4206, and the lookup table 4210(e.g., phase to amplitude converter). The content of the phaseaccumulator 4206 is updated once per clock cycle f_(c). When time thephase accumulator 4206 is updated, the digital number, M, stored in theparallel delta phase register 4204 is added to the number in the phaseregister 4208 by the adder circuit 4216. Assuming that the number in theparallel delta phase register 4204 is 00 . . . 01 and that the initialcontents of the phase accumulator 4206 is 00 . . . 00. The phaseaccumulator 4206 is updated by 00 . . . 01 per clock cycle. If the phaseaccumulator 4206 is 32-bits wide, 232 clock cycles (over 4 billion) arerequired before the phase accumulator 4206 returns to 00 . . . 00, andthe cycle repeats.

A truncated output 4218 of the phase accumulator 4206 is provided to aphase-to amplitude converter lookup table 4210 and the output of thelookup table 4210 is coupled to a DAC circuit 4212. The truncated output4218 of the phase accumulator 4206 serves as the address to a sine (orcosine) lookup table. An address in the lookup table corresponds to aphase point on the sinewave from 0° to 360°. The lookup table 4210contains the corresponding digital amplitude information for onecomplete cycle of a sinewave. The lookup table 4210 therefore maps thephase information from the phase accumulator 4206 into a digitalamplitude word, which in turn drives the DAC circuit 4212. The output ofthe DAC circuit is a first analog signal 4220 and is filtered by afilter 4214. The output of the filter 4214 is a second analog signal4222, which is provided to a power amplifier coupled to the output ofthe generator circuit.

In one aspect, the electrical signal waveform may be digitized into 1024(210) phase points, although the wave shape may be digitized is anysuitable number of 2n phase points ranging from 256 (28) to281,474,976,710,656 (248), where n is a positive integer, as shown inTABLE 1. The electrical signal waveform may be expressed asA_(n)(θ_(n)), where a normalized amplitude A_(n) at a point n isrepresented by a phase angle θ_(n) is referred to as a phase point atpoint n. The number of discrete phase points n determines the tuningresolution of the DDS circuit 4200 (as well as the DDS circuit 4100shown in FIG. 35).

TABLE 1 specifies the electrical signal waveform digitized into a numberof phase points.

TABLE 1 N Number of Phase Points 2^(n)  8 256 10 1,024 12 4,096 1416,384 16 65,536 18 262,144 20 1,048,576 22 4,194,304 24 16,777,216 2667,108,864 28 268,435,456 . . . . . . 32 4,294,967,296 . . . . . . 48281,474,976,710,656 . . . . . .

The generator circuit algorithms and digital control circuits scan theaddresses in the lookup table 4210, which in turn provides varyingdigital input values to the DAC circuit 4212 that feeds the filter 4214and the power amplifier. The addresses may be scanned according to afrequency of interest. Using the lookup table enables generating varioustypes of shapes that can be converted into an analog output signal bythe DAC circuit 4212, filtered by the filter 4214, amplified by thepower amplifier coupled to the output of the generator circuit, and fedto the tissue in the form of RF energy or fed to an ultrasonictransducer and applied to the tissue in the form of ultrasonicvibrations which deliver energy to the tissue in the form of heat. Theoutput of the amplifier can be applied to an RF electrode, multiple RFelectrodes simultaneously, an ultrasonic transducer, multiple ultrasonictransducers simultaneously, or a combination of RF and ultrasonictransducers, for example. Furthermore, multiple wave shape tables can becreated, stored, and applied to tissue from a generator circuit.

With reference back to FIG. 35, for n=32, and M=1, the phase accumulator4206 steps through 232 possible outputs before it overflows andrestarts. The corresponding output wave frequency is equal to the inputclock frequency divided by 232. If M=2, then the phase register 1708“rolls over” twice as fast, and the output frequency is doubled. Thiscan be generalized as follows.

For a phase accumulator 4206 configured to accumulate n-bits (ngenerally ranges from 24 to 32 in most DDS systems, but as previouslydiscussed n may be selected from a wide range of options), there are 2^(n) possible phase points. The digital word in the delta phaseregister, M, represents the amount the phase accumulator is incrementedper clock cycle. If f_(c) is the clock frequency, then the frequency ofthe output sinewave is equal to:

$f_{0} = \frac{M \cdot f_{c}}{2^{n}}$

The above equation is known as the DDS “tuning equation.” Note that thefrequency resolution of the system is equal to

$\frac{f_{o}}{2^{n}}.$

For n=32, the resolution is greater than one part in four billion. Inone aspect of the DDS circuit 4200, not all of the bits out of the phaseaccumulator 4206 are passed on to the lookup table 4210, but aretruncated, leaving only the first 13 to 15 most significant bits (MSBs),for example. This reduces the size of the lookup table 4210 and does notaffect the frequency resolution. The phase truncation only adds a smallbut acceptable amount of phase noise to the final output.

The electrical signal waveform may be characterized by a current,voltage, or power at a predetermined frequency. Further, where any oneof the surgical instruments of surgical system 1000 comprises ultrasoniccomponents, the electrical signal waveform may be configured to drive atleast two vibration modes of an ultrasonic transducer of the at leastone surgical instrument. Accordingly, the generator circuit may beconfigured to provide an electrical signal waveform to at least onesurgical instrument wherein the electrical signal waveform ischaracterized by a predetermined wave shape stored in the lookup table4210 (or lookup table 4104, FIG. 35). Further, the electrical signalwaveform may be a combination of two or more wave shapes. The lookuptable 4210 may comprise information associated with a plurality of waveshapes. In one aspect or example, the lookup table 4210 may be generatedby the DDS circuit 4200 and may be referred to as a direct digitalsynthesis table. DDS works by first storing a large repetitive waveformin onboard memory. A cycle of a waveform (sine, triangle, square,arbitrary) can be represented by a predetermined number of phase pointsas shown in TABLE 1 and stored into memory. Once the waveform is storedinto memory, it can be generated at very precise frequencies. The directdigital synthesis table may be stored in a non-volatile memory of thegenerator circuit and/or may be implemented with a FPGA circuit in thegenerator circuit. The lookup table 4210 may be addressed by anysuitable technique that is convenient for categorizing wave shapes.According to one aspect, the lookup table 4210 is addressed according toa frequency of the electrical signal waveform. Additionally, theinformation associated with the plurality of wave shapes may be storedas digital information in a memory or as part of the lookup table 4210.

In one aspect, the generator circuit may be configured to provideelectrical signal waveforms to at least two surgical instrumentssimultaneously. The generator circuit also may be configured to providethe electrical signal waveform, which may be characterized two or morewave shapes, via an output channel of the generator circuit to the twosurgical instruments simultaneously. For example, in one aspect theelectrical signal waveform comprises a first electrical signal to drivean ultrasonic transducer (e.g., ultrasonic drive signal), a second RFdrive signal, and/or a combination thereof. In addition, an electricalsignal waveform may comprise a plurality of ultrasonic drive signals, aplurality of RF drive signals, and/or a combination of a plurality ofultrasonic and RF drive signals.

In addition, a method of operating the generator circuit according tothe present disclosure comprises generating an electrical signalwaveform and providing the generated electrical signal waveform to anyone of the surgical instruments of surgical system 1000, wheregenerating the electrical signal waveform comprises receivinginformation associated with the electrical signal waveform from amemory. The generated electrical signal waveform comprises at least onewave shape. Furthermore, providing the generated electrical signalwaveform to the at least one surgical instrument comprises providing theelectrical signal waveform to at least two surgical instrumentssimultaneously.

The generator circuit as described herein may allow for the generationof various types of direct digital synthesis tables. Examples of waveshapes for RF/Electrosurgery signals suitable for treating a variety oftissue generated by the generator circuit include RF signals with a highcrest factor (which may be used for surface coagulation in RF mode), alow crest factor RF signals (which may be used for deeper tissuepenetration), and waveforms that promote efficient touch-up coagulation.The generator circuit also may generate multiple wave shapes employing adirect digital synthesis lookup table 4210 and, on the fly, can switchbetween particular wave shapes based on the desired tissue effect.Switching may be based on tissue impedance and/or other factors.

In addition to traditional sine /cosine wave shapes, the generatorcircuit may be configured to generate wave shape(s) that maximize thepower into tissue per cycle (i.e., trapezoidal or square wave). Thegenerator circuit may provide wave shape(s) that are synchronized tomaximize the power delivered to the load when driving RF and ultrasonicsignals simultaneously and to maintain ultrasonic frequency lock,provided that the generator circuit includes a circuit topology thatenables simultaneously driving RF and ultrasonic signals. Further,custom wave shapes specific to instruments and their tissue effects canbe stored in a non-volatile memory (NVM) or an instrument EEPROM and canbe fetched upon connecting any one of the surgical instruments ofsurgical system 1000 to the generator circuit.

The DDS circuit 4200 may comprise multiple lookup tables 4104 where thelookup table 4210 stores a waveform represented by a predeterminednumber of phase points (also may be referred to as samples), wherein thephase points define a predetermined shape of the waveform. Thus multiplewaveforms having a unique shape can be stored in multiple lookup tables4210 to provide different tissue treatments based on instrument settingsor tissue feedback. Examples of waveforms include high crest factor RFelectrical signal waveforms for surface tissue coagulation, low crestfactor RF electrical signal waveform for deeper tissue penetration, andelectrical signal waveforms that promote efficient touch-up coagulation.In one aspect, the DDS circuit 4200 can create multiple wave shapelookup tables 4210 and during a tissue treatment procedure (e.g.,“on-the-fly” or in virtual real time based on user or sensor inputs)switch between different wave shapes stored in different lookup tables4210 based on the tissue effect desired and/or tissue feedback.

Accordingly, switching between wave shapes can be based on tissueimpedance and other factors, for example. In other aspects, the lookuptables 4210 can store electrical signal waveforms shaped to maximize thepower delivered into the tissue per cycle (i.e., trapezoidal or squarewave). In other aspects, the lookup tables 4210 can store wave shapessynchronized in such way that they make maximizing power delivery by anyone of the surgical instruments of surgical system 1000 when deliveringRF and ultrasonic drive signals. In yet other aspects, the lookup tables4210 can store electrical signal waveforms to drive ultrasonic and RFtherapeutic, and/or sub-therapeutic, energy simultaneously whilemaintaining ultrasonic frequency lock. Generally, the output wave shapemay be in the form of a sine wave, cosine wave, pulse wave, square wave,and the like. Nevertheless, the more complex and custom wave shapesspecific to different instruments and their tissue effects can be storedin the non-volatile memory of the generator circuit or in thenon-volatile memory (e.g., EEPROM) of the surgical instrument and befetched upon connecting the surgical instrument to the generatorcircuit. One example of a custom wave shape is an exponentially dampedsinusoid as used in many high crest factor “coagulation” waveforms, asshown in FIG. 37.

FIG. 37 illustrates one cycle of a discrete time digital electricalsignal waveform 4300, in accordance with at least one aspect of thepresent disclosure of an analog waveform 4304 (shown superimposed overthe discrete time digital electrical signal waveform 4300 for comparisonpurposes). The horizontal axis represents Time (t) and the vertical axisrepresents digital phase points. The digital electrical signal waveform4300 is a digital discrete time version of the desired analog waveform4304, for example. The digital electrical signal waveform 4300 isgenerated by storing an amplitude phase point 4302 that represents theamplitude per clock cycle T_(clk) over one cycle or period T_(o). Thedigital electrical signal waveform 4300 is generated over one periodT_(o) by any suitable digital processing circuit. The amplitude phasepoints are digital words stored in a memory circuit. In the exampleillustrated in FIGS. 35 and 36, the digital word is a six-bit word thatis capable of storing the amplitude phase points with a resolution of 26or 64 bits. It will be appreciated that the examples shown in FIGS. 35and 36 is for illustrative purposes and in actual implementations theresolution can be much higher. The digital amplitude phase points 4302over one cycle T_(o) are stored in the memory as a string of stringwords in a lookup table 4104, 4210 as described in connection with FIGS.35 and 36, for example. To generate the analog version of the analogwaveform 4304, the amplitude phase points 4302 are read sequentiallyfrom the memory from 0 to T_(o) per clock cycle T_(clk) and areconverted by a DAC circuit 4108, 4212, also described in connection withFIGS. 35 and 36. Additional cycles can be generated by repeatedlyreading the amplitude phase points 4302 of the digital electrical signalwaveform 4300 the from 0 to T_(o) for as many cycles or periods as maybe desired. The smooth analog version of the analog waveform 4304 isachieved by filtering the output of the DAC circuit 4108, 4212 by afilter 4112, 4214 (FIGS. 35 and 36). The filtered analog output signal4114, 4222 (FIGS. 35 and 36) is applied to the input of a poweramplifier.

FIG. 38 is a diagram of a control system 12950 configured to provideprogressive closure of a closure member (e.g., closure tube) when thedisplacement member advances distally and couples into a clamp arm(e.g., anvil) to lower the closure force load on the closure member at adesired rate and decrease the firing force load on the firing memberaccording to one aspect of this disclosure. In one aspect, the controlsystem 12950 may be implemented as a nested PID feedback controller. APID controller is a control loop feedback mechanism (controller) tocontinuously calculate an error value as the difference between adesired set point and a measured process variable and applies acorrection based on proportional, integral, and derivative terms(sometimes denoted P, I, and D respectively). The nested PID controllerfeedback control system 12950 includes a primary controller 12952, in aprimary (outer) feedback loop 12954 and a secondary controller 12955 ina secondary (inner) feedback loop 12956. The primary controller 12952may be a PID controller 12972 as shown in FIG. 39, and the secondarycontroller 12955 also may be a PID controller 12972 as shown in FIG. 39.The primary controller 12952 controls a primary process 12958 and thesecondary controller 12955 controls a secondary process 12960. Theoutput 12966 of the primary process 12958 is subtracted from a primaryset point SP₁ by a first summer 12962. The first summer 12962 produces asingle sum output signal which is applied to the primary controller12952. The output of the primary controller 12952 is the secondary setpoint SP₂. The output 12968 of the secondary process 12960 is subtractedfrom the secondary set point SP₂ by a second summer 12964.

In the context of controlling the displacement of a closure tube, thecontrol system 12950 may be configured such that the primary set pointSP₁ is a desired closure force value and the primary controller 12952 isconfigured to receive the closure force from a torque sensor coupled tothe output of a closure motor and determine a set point SP₂ motorvelocity for the closure motor. In other aspects, the closure force maybe measured with strain gauges, load cells, or other suitable forcesensors. The closure motor velocity set point SP₂ is compared to theactual velocity of the closure tube, which is determined by thesecondary controller 12955. The actual velocity of the closure tube maybe measured by comparing measuring the displacement of the closure tubewith the position sensor and measuring elapsed time with atimer/counter. Other techniques, such as linear or rotary encoders maybe employed to measure displacement of the closure tube. The output12968 of the secondary process 12960 is the actual velocity of theclosure tube. This closure tube velocity output 12968 is provided to theprimary process 12958 which determines the force acting on the closuretube and is fed back to the adder 12962, which subtracts the measuredclosure force from the primary set point SP₁. The primary set point SP₁may be an upper threshold or a lower threshold. Based on the output ofthe adder 12962, the primary controller 12952 controls the velocity anddirection of the closure motor. The secondary controller 12955 controlsthe velocity of the closure motor based on the actual velocity ofclosure tube measured by the secondary process 12960 and the secondaryset point SP₂, which is based on a comparison of the actual firing forceand the firing force upper and lower thresholds.

FIG. 39 illustrates a PID feedback control system 12970 according to oneaspect of this disclosure. The primary controller 12952 or the secondarycontroller 12955, or both, may be implemented as a PID controller 12972.In one aspect, the PID controller 12972 may comprise a proportionalelement 12974 (P), an integral element 12976 (I), and a derivativeelement 12978 (D). The outputs of the P, I, D elements 12974, 12976,12978 are summed by a summer 12986, which provides the control variableμ(t) to the process 12980. The output of the process 12980 is theprocess variable y(t). A summer 12984 calculates the difference betweena desired set point r(t) and a measured process variable y(t). The PIDcontroller 12972 continuously calculates an error value e(t) (e.g.,difference between closure force threshold and measured closure force)as the difference between a desired set point r(t) (e.g., closure forcethreshold) and a measured process variable y(t) (e.g., velocity anddirection of closure tube) and applies a correction based on theproportional, integral, and derivative terms calculated by theproportional element 12974 (P), integral element 12976 (I), andderivative element 12978 (D), respectively. The PID controller 12972attempts to minimize the error e(t) over time by adjustment of thecontrol variable μ(t) (e.g., velocity and direction of the closuretube).

In accordance with the PID algorithm, the “P” element 12974 accounts forpresent values of the error. For example, if the error is large andpositive, the control output will also be large and positive. Inaccordance with the present disclosure, the error term e(t) is thedifferent between the desired closure force and the measured closureforce of the closure tube. The “I” element 12976 accounts for pastvalues of the error. For example, if the current output is notsufficiently strong, the integral of the error will accumulate overtime, and the controller will respond by applying a stronger action. The“D” element 12978 accounts for possible future trends of the error,based on its current rate of change. For example, continuing the Pexample above, when the large positive control output succeeds inbringing the error closer to zero, it also puts the process on a path tolarge negative error in the near future. In this case, the derivativeturns negative and the D module reduces the strength of the action toprevent this overshoot.

It will be appreciated that other variables and set points may bemonitored and controlled in accordance with the feedback control systems12950, 12970. For example, the adaptive closure member velocity controlalgorithm described herein may measure at least two of the followingparameters: firing member stroke location, firing member load,displacement of cutting element, velocity of cutting element, closuretube stroke location, closure tube load, among others.

Ultrasonic surgical devices, such as ultrasonic scalpels, are findingincreasingly widespread applications in surgical procedures by virtue oftheir unique performance characteristics. Depending upon specific deviceconfigurations and operational parameters, ultrasonic surgical devicescan provide substantially simultaneous transection of tissue andhomeostasis by coagulation, desirably minimizing patient trauma. Anultrasonic surgical device may comprise a handpiece containing anultrasonic transducer, and an instrument coupled to the ultrasonictransducer having a distally-mounted end effector (e.g., a blade tip) tocut and seal tissue. In some cases, the instrument may be permanentlyaffixed to the handpiece. In other cases, the instrument may bedetachable from the handpiece, as in the case of a disposable instrumentor an interchangeable instrument. The end effector transmits ultrasonicenergy to tissue brought into contact with the end effector to realizecutting and sealing action. Ultrasonic surgical devices of this naturecan be configured for open surgical use, laparoscopic, or endoscopicsurgical procedures including robotic-assisted procedures.

Ultrasonic energy cuts and coagulates tissue using temperatures lowerthan those used in electrosurgical procedures and can be transmitted tothe end effector by an ultrasonic generator in communication with thehandpiece. Vibrating at high frequencies (e.g., 55,500 cycles persecond), the ultrasonic blade denatures protein in the tissue to form asticky coagulum. Pressure exerted on tissue by the blade surfacecollapses blood vessels and allows the coagulum to form a hemostaticseal. A surgeon can control the cutting speed and coagulation by theforce applied to the tissue by the end effector, the time over which theforce is applied, and the selected excursion level of the end effector.

The ultrasonic transducer may be modeled as an equivalent circuitcomprising a first branch having a static capacitance and a second“motional” branch having a serially connected inductance, resistance andcapacitance that define the electromechanical properties of a resonator.Known ultrasonic generators may include a tuning inductor for tuning outthe static capacitance at a resonant frequency so that substantially allof a generator's drive signal current flows into the motional branch.Accordingly, by using a tuning inductor, the generator's drive signalcurrent represents the motional branch current, and the generator isthus able to control its drive signal to maintain the ultrasonictransducer's resonant frequency. The tuning inductor may also transformthe phase impedance plot of the ultrasonic transducer to improve thegenerator's frequency lock capabilities. However, the tuning inductormust be matched with the specific static capacitance of an ultrasonictransducer at the operational resonant frequency. In other words, adifferent ultrasonic transducer having a different static capacitancerequires a different tuning inductor.

Additionally, in some ultrasonic generator architectures, thegenerator's drive signal exhibits asymmetrical harmonic distortion thatcomplicates impedance magnitude and phase measurements. For example, theaccuracy of impedance phase measurements may be reduced due to harmonicdistortion in the current and voltage signals.

Moreover, electromagnetic interference in noisy environments decreasesthe ability of the generator to maintain lock on the ultrasonictransducer's resonant frequency, increasing the likelihood of invalidcontrol algorithm inputs.

Electrosurgical devices for applying electrical energy to tissue inorder to treat and/or destroy the tissue are also finding increasinglywidespread applications in surgical procedures. An electrosurgicaldevice may comprise a handpiece and an instrument having adistally-mounted end effector (e.g., one or more electrodes). The endeffector can be positioned against the tissue such that electricalcurrent is introduced into the tissue. Electrosurgical devices can beconfigured for bipolar or monopolar operation. During bipolar operation,current is introduced into and returned from the tissue by active andreturn electrodes, respectively, of the end effector. During monopolaroperation, current is introduced into the tissue by an active electrodeof the end effector and returned through a return electrode (e.g., agrounding pad) separately located on a patient's body. Heat generated bythe current flowing through the tissue may form hemostatic seals withinthe tissue and/or between tissues and thus may be particularly usefulfor sealing blood vessels, for example. The end effector of anelectrosurgical device may also comprise a cutting member that ismovable relative to the tissue and the electrodes to transect thetissue.

Electrical energy applied by an electrosurgical device can betransmitted to the instrument by a generator in communication with thehandpiece. The electrical energy may be in the form of radio frequency(RF) energy. RF energy is a form of electrical energy that may be in thefrequency range of 300 kHz to 1 MHz, as described inEN60601-2-2:2009+A11:2011, Definition 201.3.218—HIGH FREQUENCY. Forexample, the frequencies in monopolar RF applications are typicallyrestricted to less than 5 MHz. However, in bipolar RF applications, thefrequency can be almost any value. Frequencies above 200 kHz aretypically used for monopolar applications in order to avoid the unwantedstimulation of nerves and muscles which would result from the use of lowfrequency current. Lower frequencies may be used for bipolar techniquesif a risk analysis shows the possibility of neuromuscular stimulationhas been mitigated to an acceptable level. Normally, frequencies above 5MHz are not used in order to minimize the problems associated with highfrequency leakage currents. It is generally recognized that 10 mA is thelower threshold of thermal effects on tissue.

During its operation, an electrosurgical device can transmit lowfrequency RF energy through tissue, which causes ionic agitation, orfriction, in effect resistive heating, thereby increasing thetemperature of the tissue. Because a sharp boundary may be createdbetween the affected tissue and the surrounding tissue, surgeons canoperate with a high level of precision and control, without sacrificingun-targeted adjacent tissue. The low operating temperatures of RF energymay be useful for removing, shrinking, or sculpting soft tissue whilesimultaneously sealing blood vessels. RF energy may work particularlywell on connective tissue, which is primarily comprised of collagen andshrinks when contacted by heat.

Due to their unique drive signal, sensing and feedback needs, ultrasonicand electrosurgical devices have generally required differentgenerators. Additionally, in cases where the instrument is disposable orinterchangeable with a handpiece, ultrasonic and electrosurgicalgenerators are limited in their ability to recognize the particularinstrument configuration being used and to optimize control anddiagnostic processes accordingly. Moreover, capacitive coupling betweenthe non-isolated and patient-isolated circuits of the generator,especially in cases where higher voltages and frequencies are used, mayresult in exposure of a patient to unacceptable levels of leakagecurrent.

Furthermore, due to their unique drive signal, sensing and feedbackneeds, ultrasonic and electrosurgical devices have generally requireddifferent user interfaces for the different generators. In suchconventional ultrasonic and electrosurgical devices, one user interfaceis configured for use with an ultrasonic instrument whereas a differentuser interface may be configured for use with an electrosurgicalinstrument. Such user interfaces include hand and/or foot activated userinterfaces such as hand activated switches and/or foot activatedswitches. As various aspects of combined generators for use with bothultrasonic and electrosurgical instruments are contemplated in thesubsequent disclosure, additional user interfaces that are configured tooperate with both ultrasonic and/or electrosurgical instrumentgenerators also are contemplated.

Additional user interfaces for providing feedback, whether to the useror other machine, are contemplated within the subsequent disclosure toprovide feedback indicating an operating mode or status of either anultrasonic and/or electrosurgical instrument. Providing user and/ormachine feedback for operating a combination ultrasonic and/orelectrosurgical instrument will require providing sensory feedback to auser and electrical/mechanical/electro-mechanical feedback to a machine.Feedback devices that incorporate visual feedback devices (e.g., an LCDdisplay screen, LED indicators), audio feedback devices (e.g., aspeaker, a buzzer) or tactile feedback devices (e.g., haptic actuators)for use in combined ultrasonic and/or electrosurgical instruments arecontemplated in the subsequent disclosure.

Other electrical surgical instruments include, without limitation,irreversible and/or reversible electroporation, and/or microwavetechnologies, among others. Accordingly, the techniques disclosed hereinare applicable to ultrasonic, bipolar or monopolar RF (electrosurgical),irreversible and/or reversible electroporation, and/or microwave basedsurgical instruments, among others.

Various aspects are directed to improved ultrasonic surgical devices,electrosurgical devices and generators for use therewith. Aspects of theultrasonic surgical devices can be configured for transecting and/orcoagulating tissue during surgical procedures, for example. Aspects ofthe electrosurgical devices can be configured for transecting,coagulating, scaling, welding and/or desiccating tissue during surgicalprocedures, for example.

Aspects of the generator utilize high-speed analog-to-digital sampling(e.g., approximately 200× oversampling, depending on frequency) of thegenerator drive signal current and voltage, along with digital signalprocessing, to provide a number of advantages and benefits over knowngenerator architectures. In one aspect, for example, based on currentand voltage feedback data, a value of the ultrasonic transducer staticcapacitance, and a value of the drive signal frequency, the generatormay determine the motional branch current of an ultrasonic transducer.This provides the benefit of a virtually tuned system, and simulates thepresence of a system that is tuned or resonant with any value of thestatic capacitance (e.g., C₀ in FIG. 25) at any frequency. Accordingly,control of the motional branch current may be realized by tuning out theeffects of the static capacitance without the need for a tuninginductor. Additionally, the elimination of the tuning inductor may notdegrade the generator's frequency lock capabilities, as frequency lockcan be realized by suitably processing the current and voltage feedbackdata.

High-speed analog-to-digital sampling of the generator drive signalcurrent and voltage, along with digital signal processing, may alsoenable precise digital filtering of the samples. For example, aspects ofthe generator may utilize a low-pass digital filter (e.g., a finiteimpulse response (FIR) filter) that rolls off between a fundamentaldrive signal frequency and a second-order harmonic to reduce theasymmetrical harmonic distortion and EMI-induced noise in current andvoltage feedback samples. The filtered current and voltage feedbacksamples represent substantially the fundamental drive signal frequency,thus enabling a more accurate impedance phase measurement with respectto the fundamental drive signal frequency and an improvement in thegenerator's ability to maintain resonant frequency lock. The accuracy ofthe impedance phase measurement may be further enhanced by averagingfalling edge and rising edge phase measurements, and by regulating themeasured impedance phase to 0°.

Various aspects of the generator may also utilize the high-speedanalog-to-digital sampling of the generator drive signal current andvoltage, along with digital signal processing, to determine real powerconsumption and other quantities with a high degree of precision. Thismay allow the generator to implement a number of useful algorithms, suchas, for example, controlling the amount of power delivered to tissue asthe impedance of the tissue changes and controlling the power deliveryto maintain a constant rate of tissue impedance increase. Some of thesealgorithms are used to determine the phase difference between thegenerator drive signal current and voltage signals. At resonance, thephase difference between the current and voltage signals is zero. Thephase changes as the ultrasonic system goes off-resonance. Variousalgorithms may be employed to detect the phase difference and adjust thedrive frequency until the ultrasonic system returns to resonance, i.e.,the phase difference between the current and voltage signals goes tozero. The phase information also may be used to infer the conditions ofthe ultrasonic blade. As discussed with particularity below, the phasechanges as a function of the temperature of the ultrasonic blade.Therefore, the phase information may be employed to control thetemperature of the ultrasonic blade. This may be done, for example, byreducing the power delivered to the ultrasonic blade when the ultrasonicblade runs too hot and increasing the power delivered to the ultrasonicblade when the ultrasonic blade runs too cold.

Various aspects of the generator may have a wide frequency range andincreased output power necessary to drive both ultrasonic surgicaldevices and electrosurgical devices. The lower voltage, higher currentdemand of electrosurgical devices may be met by a dedicated tap on awideband power transformer, thereby eliminating the need for a separatepower amplifier and output transformer. Moreover, sensing and feedbackcircuits of the generator may support a large dynamic range thataddresses the needs of both ultrasonic and electrosurgical applicationswith minimal distortion.

Various aspects may provide a simple, economical means for the generatorto read from, and optionally write to, a data circuit (e.g., asingle-wire bus device, such as a one-wire protocol EEPROM known underthe trade name “1-Wire”) disposed in an instrument attached to thehandpiece using existing multi-conductor generator/handpiece cables. Inthis way, the generator is able to retrieve and processinstrument-specific data from an instrument attached to the handpiece.This may enable the generator to provide better control and improveddiagnostics and error detection. Additionally, the ability of thegenerator to write data to the instrument makes possible newfunctionality in terms of, for example, tracking instrument usage andcapturing operational data. Moreover, the use of frequency band permitsthe backward compatibility of instruments containing a bus device withexisting generators.

Disclosed aspects of the generator provide active cancellation ofleakage current caused by unintended capacitive coupling betweennon-isolated and patient-isolated circuits of the generator. In additionto reducing patient risk, the reduction of leakage current may alsolessen electromagnetic emissions.

FIG. 40 is a system diagram 7400 of a segmented circuit 7401 comprisinga plurality of independently operated circuit segments 7402, 7414, 7416,7420, 7424, 7428, 7434, 7440, in accordance with at least one aspect ofthe present disclosure. A circuit segment of the plurality of circuitsegments of the segmented circuit 7401 comprises one or more circuitsand one or more sets of machine executable instructions stored in one ormore memory devices. The one or more circuits of a circuit segment arecoupled to for electrical communication through one or more wired orwireless connection media. The plurality of circuit segments areconfigured to transition between three modes comprising a sleep mode, astandby mode and an operational mode.

In one aspect shown, the plurality of circuit segments 7402, 7414, 7416,7420, 7424, 7428, 7434, 7440 start first in the standby mode, transitionsecond to the sleep mode, and transition third to the operational mode.However, in other aspects, the plurality of circuit segments maytransition from any one of the three modes to any other one of the threemodes. For example, the plurality of circuit segments may transitiondirectly from the standby mode to the operational mode. Individualcircuit segments may be placed in a particular state by the voltagecontrol circuit 7408 based on the execution by a processor of machineexecutable instructions. The states comprise a deenergized state, a lowenergy state, and an energized state. The deenergized state correspondsto the sleep mode, the low energy state corresponds to the standby mode,and the energized state corresponds to the operational mode. Transitionto the low energy state may be achieved by, for example, the use of apotentiometer.

In one aspect, the plurality of circuit segments 7402, 7414, 7416, 7420,7424, 7428, 7434, 7440 may transition from the sleep mode or the standbymode to the operational mode in accordance with an energizationsequence. The plurality of circuit segments also may transition from theoperational mode to the standby mode or the sleep mode in accordancewith a deenergization sequence. The energization sequence and thedeenergization sequence may be different. In some aspects, theenergization sequence comprises energizing only a subset of circuitsegments of the plurality of circuit segments. In some aspects, thedeenergization sequence comprises deenergizing only a subset of circuitsegments of the plurality of circuit segments.

Referring back to the system diagram 7400 in FIG. 40, the segmentedcircuit 7401 comprise a plurality of circuit segments comprising atransition circuit segment 7402, a processor circuit segment 7414, ahandle circuit segment 7416, a communication circuit segment 7420, adisplay circuit segment 7424, a motor control circuit segment 7428, anenergy treatment circuit segment 7434, and a shaft circuit segment 7440.The transition circuit segment comprises a wake up circuit 7404, a boostcurrent circuit 7406, a voltage control circuit 7408, a safetycontroller 7410 and a POST controller 7412. The transition circuitsegment 7402 is configured to implement a deenergization and anenergization sequence, a safety detection protocol, and a POST.

In some aspects, the wake up circuit 7404 comprises an accelerometerbutton sensor 7405. In aspects, the transition circuit segment 7402 isconfigured to be in an energized state while other circuit segments ofthe plurality of circuit segments of the segmented circuit 7401 areconfigured to be in a low energy state, a deenergized state or anenergized state. The accelerometer button sensor 7405 may monitormovement or acceleration of the surgical instrument 6480 describedherein. For example, the movement may be a change in orientation orrotation of the surgical instrument. The surgical instrument may bemoved in any direction relative to a three dimensional Euclidean spaceby for example, a user of the surgical instrument. When theaccelerometer button sensor 7405 senses movement or acceleration, theaccelerometer button sensor 7405 sends a signal to the voltage controlcircuit 7408 to cause the voltage control circuit 7408 to apply voltageto the processor circuit segment 7414 to transition the processor and avolatile memory to an energized state. In aspects, the processor and thevolatile memory are in an energized state before the voltage controlcircuit 7409 applies voltage to the processor and the volatile memory.In the operational mode, the processor may initiate an energizationsequence or a deenergization sequence. In various aspects, theaccelerometer button sensor 7405 may also send a signal to the processorto cause the processor to initiate an energization sequence or adeenergization sequence. In some aspects, the processor initiates anenergization sequence when the majority of individual circuit segmentsare in a low energy state or a deenergized state. In other aspects, theprocessor initiates a deenergization sequence when the majority ofindividual circuit segments are in an energized state.

Additionally or alternatively, the accelerometer button sensor 7405 maysense external movement within a predetermined vicinity of the surgicalinstrument. For example, the accelerometer button sensor 7405 may sensea user of the surgical instrument 6480 described herein moving a hand ofthe user within the predetermined vicinity. When the accelerometerbutton sensor 7405 senses this external movement, the accelerometerbutton sensor 7405 may send a signal to the voltage control circuit 7408and a signal to the processor, as previously described. After receivingthe sent signal, the processor may initiate an energization sequence ora deenergization sequence to transition one or more circuit segmentsbetween the three modes. In aspects, the signal sent to the voltagecontrol circuit 7408 is sent to verify that the processor is inoperational mode. In some aspects, the accelerometer button sensor 7405may sense when the surgical instrument has been dropped and send asignal to the processor based on the sensed drop. For example, thesignal can indicate an error in the operation of an individual circuitsegment. One or more sensors may sense damage or malfunctioning of theaffected individual circuit segments. Based on the sensed damage ormalfunctioning, the POST controller 7412 may perform a POST of thecorresponding individual circuit segments.

An energization sequence or a deenergization sequence may be definedbased on the accelerometer button sensor 7405. For example, theaccelerometer button sensor 7405 may sense a particular motion or asequence of motions that indicates the selection of a particular circuitsegment of the plurality of circuit segments. Based on the sensed motionor series of sensed motions, the accelerometer button sensor 7405 maytransmit a signal comprising an indication of one or more circuitsegments of the plurality of circuit segments to the processor when theprocessor is in an energized state. Based on the signal, the processordetermines an energization sequence comprising the selected one or morecircuit segments. Additionally or alternatively, a user of the surgicalinstruments 6480 described herein may select a number and order ofcircuit segments to define an energization sequence or a deenergizationsequence based on interaction with a graphical user interface (GUI) ofthe surgical instrument.

In various aspects, the accelerometer button sensor 7405 may send asignal to the voltage control circuit 7408 and a signal to the processoronly when the accelerometer button sensor 7405 detects movement of thesurgical instrument 6480 described herein or external movement within apredetermined vicinity above a predetermined threshold. For example, asignal may only be sent if movement is sensed for 5 or more seconds orif the surgical instrument is moved 5 or more inches. In other aspects,the accelerometer button sensor 7405 may send a signal to the voltagecontrol circuit 7408 and a signal to the processor only when theaccelerometer button sensor 7405 detects oscillating movement of thesurgical instrument. A predetermined threshold reduces inadvertenttransition of circuit segments of the surgical instrument. As previouslydescribed, the transition may comprise a transition to operational modeaccording to an energization sequence, a transition to low energy modeaccording to a deenergization sequence, or a transition to sleep modeaccording to a deenergization sequence. In some aspects, the surgicalinstrument comprises an actuator that may be actuated by a user of thesurgical instrument. The actuation is sensed by the accelerometer buttonsensor 7405. The actuator may be a slider, a toggle switch, or amomentary contact switch. Based on the sensed actuation, theaccelerometer button sensor 7405 may send a signal to the voltagecontrol circuit 7408 and a signal to the processor.

The boost current circuit 7406 is coupled to a battery. The boostcurrent circuit 7406 is a current amplifier, such as a relay ortransistor, and is configured to amplify the magnitude of a current ofan individual circuit segment. The initial magnitude of the currentcorresponds to the source voltage provided by the battery to thesegmented circuit 7401. Suitable relays include solenoids. Suitabletransistors include field-effect transistors (FET), MOSFET, and bipolarjunction transistors (BJT). The boost current circuit 7406 may amplifythe magnitude of the current corresponding to an individual circuitsegment or circuit which requires more current draw during operation ofthe surgical instruments 6480 described herein. For example, an increasein current to the motor control circuit segment 7428 may be providedwhen a motor of the surgical instrument requires more input power. Theincrease in current provided to an individual circuit segment may causea corresponding decrease in current of another circuit segment orcircuit segments. Additionally or alternatively, the increase in currentmay correspond to voltage provided by an additional voltage sourceoperating in conjunction with the battery.

The voltage control circuit 7408 is coupled to the battery. The voltagecontrol circuit 7408 is configured to provide voltage to or removevoltage from the plurality of circuit segments. The voltage controlcircuit 7408 is also configured to increase or reduce voltage providedto the plurality of circuit segments of the segmented circuit 7401. Invarious aspects, the voltage control circuit 7408 comprises acombinational logic circuit such as a multiplexer (MUX) to selectinputs, a plurality of electronic switches, and a plurality of voltageconverters. An electronic switch of the plurality of electronic switchesmay be configured to switch between an open and closed configuration todisconnect or connect an individual circuit segment to or from thebattery. The plurality of electronic switches may be solid state devicessuch as transistors or other types of switches such as wirelessswitches, ultrasonic switches, accelerometers, inertial sensors, amongothers. The combinational logic circuit is configured to select anindividual electronic switch for switching to an open configuration toenable application of voltage to the corresponding circuit segment. Thecombination logic circuit also is configured to select an individualelectronic switch for switching to a closed configuration to enableremoval of voltage from the corresponding circuit segment. By selectinga plurality of individual electronic switches, the combination logiccircuit may implement a deenergization sequence or an energizationsequence. The plurality of voltage converters may provide a stepped-upvoltage or a stepped-down voltage to the plurality of circuit segments.The voltage control circuit 7408 may also comprise a microprocessor andmemory device.

The safety controller 7410 is configured to perform safety checks forthe circuit segments. In some aspects, the safety controller 7410performs the safety checks when one or more individual circuit segmentsare in the operational mode. The safety checks may be performed todetermine whether there are any errors or defects in the functioning oroperation of the circuit segments. The safety controller 7410 maymonitor one or more parameters of the plurality of circuit segments. Thesafety controller 7410 may verify the identity and operation of theplurality of circuit segments by comparing the one or more parameterswith predefined parameters. For example, if an RF energy modality isselected, the safety controller 7410 may verify that an articulationparameter of the shaft matches a predefined articulation parameter toverify the operation of the RF energy modality of the surgicalinstrument 6480 described herein. In some aspects, the safety controller7410 may monitor, by the sensors, a predetermined relationship betweenone or more properties of the surgical instrument to detect a fault. Afault may arise when the one or more properties are inconsistent withthe predetermined relationship. When the safety controller 7410determines that a fault exists, an error exists, or that some operationof the plurality of circuit segments was not verified, the safetycontroller 7410 prevents or disables operation of the particular circuitsegment where the fault, error or verification failure originated.

The POST controller 7412 performs a POST to verify proper operation ofthe plurality of circuit segments. In some aspects, the POST isperformed for an individual circuit segment of the plurality of circuitsegments prior to the voltage control circuit 7408 applying a voltage tothe individual circuit segment to transition the individual circuitsegment from standby mode or sleep mode to operational mode. If theindividual circuit segment does not pass the POST, the particularcircuit segment does not transition from standby mode or sleep mode tooperational mode. POST of the handle circuit segment 7416 may comprise,for example, testing whether the handle control sensors 7418 sense anactuation of a handle control of the surgical instrument 6480 describedherein. In some aspects, the POST controller 7412 may transmit a signalto the accelerometer button sensor 7405 to verify the operation of theindividual circuit segment as part of the POST. For example, afterreceiving the signal, the accelerometer button sensor 7405 may prompt auser of the surgical instrument to move the surgical instrument to aplurality of varying locations to confirm operation of the surgicalinstrument. The accelerometer button sensor 7405 may also monitor anoutput of a circuit segment or a circuit of a circuit segment as part ofthe POST. For example, the accelerometer button sensor 7405 can sense anincremental motor pulse generated by the motor 7432 to verify operation.A motor controller of the motor control circuit 7430 may be used tocontrol the motor 7432 to generate the incremental motor pulse.

In various aspects, the surgical instrument 6480 described herein maycomprise additional accelerometer button sensors. The POST controller7412 may also execute a control program stored in the memory device ofthe voltage control circuit 7408. The control program may cause the POSTcontroller 7412 to transmit a signal requesting a matching encryptedparameter from a plurality of circuit segments. Failure to receive amatching encrypted parameter from an individual circuit segmentindicates to the POST controller 7412 that the corresponding circuitsegment is damaged or malfunctioning. In some aspects, if the POSTcontroller 7412 determines based on the POST that the processor isdamaged or malfunctioning, the POST controller 7412 may send a signal toone or more secondary processors to cause one or more secondaryprocessors to perform critical functions that the processor is unable toperform. In some aspects, if the POST controller 7412 determines basedon the POST that one or more circuit segments do not operate properly,the POST controller 7412 may initiate a reduced performance mode ofthose circuit segments operating properly while locking out thosecircuit segments that fail POST or do not operate properly. A locked outcircuit segment may function similarly to a circuit segment in standbymode or sleep mode.

The processor circuit segment 7414 comprises the processor and thevolatile memory. The processor is configured to initiate an energizationor a deenergization sequence. To initiate the energization sequence, theprocessor transmits an energizing signal to the voltage control circuit7408 to cause the voltage control circuit 7408 to apply voltage to theplurality or a subset of the plurality of circuit segments in accordancewith the energization sequence. To initiate the deenergization sequence,the processor transmits a deenergizing signal to the voltage controlcircuit 7408 to cause the voltage control circuit 7408 to remove voltagefrom the plurality or a subset of the plurality of circuit segments inaccordance with the deenergization sequence.

The handle circuit segment 7416 comprises handle control sensors 7418.The handle control sensors 7418 may sense an actuation of one or morehandle controls of the surgical instrument 6480 described herein. Invarious aspects, the one or more handle controls comprise a clampcontrol, a release button, an articulation switch, an energy activationbutton, and/or any other suitable handle control. The user may activatethe energy activation button to select between an RF energy mode, anultrasonic energy mode or a combination RF and ultrasonic energy mode.The handle control sensors 7418 may also facilitate attaching a modularhandle to the surgical instrument. For example, the handle controlsensors 7418 may sense proper attachment of the modular handle to thesurgical instrument and indicate the sensed attachment to a user of thesurgical instrument. The LCD display 7426 may provide a graphicalindication of the sensed attachment. In some aspects, the handle controlsensors 7418 senses actuation of the one or more handle controls. Basedon the sensed actuation, the processor may initiate either anenergization sequence or a deenergization sequence.

The communication circuit segment 7420 comprises a communication circuit7422. The communication circuit 7422 comprises a communication interfaceto facilitate signal communication between the individual circuitsegments of the plurality of circuit segments. In some aspects, thecommunication circuit 7422 provides a path for the modular components ofthe surgical instrument 6480 described herein to communicateelectrically. For example, a modular shaft and a modular transducer,when attached together to the handle of the surgical instrument, canupload control programs to the handle through the communication circuit7422.

The display circuit segment 7424 comprises a LCD display 7426. The LCDdisplay 7426 may comprise a liquid crystal display screen, LEDindicators, etc. In some aspects, the LCD display 7426 is an organiclight-emitting diode (OLED) screen. A display may be placed on, embeddedin, or located remotely from the surgical instrument 6480 describedherein. For example, the display can be placed on the handle of thesurgical instrument. The display is configured to provide sensoryfeedback to a user. In various aspects, the LCD display 7426 furthercomprises a backlight. In some aspects, the surgical instrument may alsocomprise audio feedback devices such as a speaker or a buzzer andtactile feedback devices such as a haptic actuator.

The motor control circuit segment 7428 comprises a motor control circuit7430 coupled to a motor 7432. The motor 7432 is coupled to the processorby a driver and a transistor, such as a FET. In various aspects, themotor control circuit 7430 comprises a motor current sensor in signalcommunication with the processor to provide a signal indicative of ameasurement of the current draw of the motor to the processor. Theprocessor transmits the signal to the display. The display receives thesignal and displays the measurement of the current draw of the motor7432. The processor may use the signal, for example, to monitor that thecurrent draw of the motor 7432 exists within an acceptable range, tocompare the current draw to one or more parameters of the plurality ofcircuit segments, and to determine one or more parameters of a patienttreatment site. In various aspects, the motor control circuit 7430comprises a motor controller to control the operation of the motor. Forexample, the motor control circuit 7430 controls various motorparameters, such as by adjusting the velocity, torque and accelerationof the motor 7432. The adjusting is done based on the current throughthe motor 7432 measured by the motor current sensor.

In various aspects, the motor control circuit 7430 comprises a forcesensor to measure the force and torque generated by the motor 7432. Themotor 7432 is configured to actuate a mechanism of the surgicalinstruments 6480 described herein. For example, the motor 7432 isconfigured to control actuation of the shaft of the surgical instrumentto realize clamping, rotation and articulation functionality. Forexample, the motor 7432 may actuate the shaft to realize a clampingmotion with jaws of the surgical instrument. The motor controller maydetermine whether the material clamped by the jaws is tissue or metal.The motor controller may also determine the extent to which the jawsclamp the material. For example, the motor controller may determine howopen or closed the jaws are based on the derivative of sensed motorcurrent or motor voltage. In some aspects, the motor 7432 is configuredto actuate the transducer to cause the transducer to apply torque to thehandle or to control articulation of the surgical instrument. The motorcurrent sensor may interact with the motor controller to set a motorcurrent limit. When the current meets the predefined threshold limit,the motor controller initiates a corresponding change in a motor controloperation. For example, exceeding the motor current limit causes themotor controller to reduce the current draw of the motor.

The energy treatment circuit segment 7434 comprises a RF amplifier andsafety circuit 7436 and an ultrasonic signal generator circuit 7438 toimplement the energy modular functionality of the surgical instrument6480 described herein. In various aspects, the RF amplifier and safetycircuit 7436 is configured to control the RF modality of the surgicalinstrument by generating an RF signal. The ultrasonic signal generatorcircuit 7438 is configured to control the ultrasonic energy modality bygenerating an ultrasonic signal. The RF amplifier and safety circuit7436 and an ultrasonic signal generator circuit 7438 may operate inconjunction to control the combination RF and ultrasonic energymodality.

The shaft circuit segment 7440 comprises a shaft module controller 7442,a modular control actuator 7444, one or more end effector sensors 7446,and a non volatile memory 7448. The shaft module controller 7442 isconfigured to control a plurality of shaft modules comprising thecontrol programs to be executed by the processor. The plurality of shaftmodules implements a shaft modality, such as ultrasonic, combinationultrasonic and RF, RF I-blade, and RF-opposable jaw. The shaft modulecontroller 7442 can select shaft modality by selecting the correspondingshaft module for the processor to execute. The modular control actuator7444 is configured to actuate the shaft according to the selected shaftmodality. After actuation is initiated, the shaft articulates the endeffector according to the one or more parameters, routines or programsspecific to the selected shaft modality and the selected end effectormodality. The one or more end effector sensors 7446 located at the endeffector may include force sensors, temperature sensors, current sensorsor motion sensors. The one or more end effector sensors 7446 transmitdata about one or more operations of the end effector, based on theenergy modality implemented by the end effector. In various aspects, theenergy modalities include an ultrasonic energy modality, a RF energymodality, or a combination of the ultrasonic energy modality and the RFenergy modality. The non volatile memory 7448 stores the shaft controlprograms. A control program comprises one or more parameters, routinesor programs specific to the shaft. In various aspects, the non volatilememory 7448 may be an ROM, EPROM, EEPROM or flash memory. The nonvolatile memory 7448 stores the shaft modules corresponding to theselected shaft of the surgical instrument 6480 described herein in. Theshaft modules may be changed or upgraded in the non volatile memory 7448by the shaft module controller 7442, depending on the surgicalinstrument shaft to be used in operation.

FIG. 41 is a schematic diagram of a circuit 7925 of various componentsof a surgical instrument with motor control functions, in accordancewith at least one aspect of the present disclosure. In various aspects,the surgical instrument 6480 described herein may include a drivemechanism 7930 which is configured to drive shafts and/or gearcomponents in order to perform the various operations associated withthe surgical instrument 6480. In one aspect, the drive mechanism 7930includes a rotation drivetrain 7932 configured to rotate an endeffector, for example, about a longitudinal axis relative to handlehousing. The drive mechanism 7930 further includes a closure drivetrain7934 configured to close a jaw member to grasp tissue with the endeffector. In addition, the drive mechanism 7930 includes a firing drivetrain 7936 configured to open and close a clamp arm portion of the endeffector to grasp tissue with the end effector.

The drive mechanism 7930 includes a selector gearbox assembly 7938 thatcan be located in the handle assembly of the surgical instrument.Proximal to the selector gearbox assembly 7938 is a function selectionmodule which includes a first motor 7942 that functions to selectivelymove gear elements within the selector gearbox assembly 7938 toselectively position one of the drivetrains 7932, 7934, 7936 intoengagement with an input drive component of an optional second motor7944 and motor drive circuit 7946 (shown in dashed line to indicate thatthe second motor 7944 and motor drive circuit 7946 are optionalcomponents).

Still referring to FIG. 41, the motors 7942, 7944 are coupled to motorcontrol circuits 7946, 7948, respectively, which are configured tocontrol the operation of the motors 7942, 7944 including the flow ofelectrical energy from a power source 7950 to the motors 7942, 7944. Thepower source 7950 may be a DC battery (e.g., rechargeable lead-based,nickel-based, lithium-ion based, battery etc.) or any other power sourcesuitable for providing electrical energy to the surgical instrument.

The surgical instrument further includes a microcontroller 7952(“controller”). In certain instances, the controller 7952 may include amicroprocessor 7954 (“processor”) and one or more computer readablemediums or memory units 7956 (“memory”). In certain instances, thememory 7956 may store various program instructions, which when executedmay cause the processor 7954 to perform a plurality of functions and/orcalculations described herein. The power source 7950 can be configuredto supply power to the controller 7952, for example.

The processor 7954 may be in communication with the motor controlcircuit 7946. In addition, the memory 7956 may store programinstructions, which when executed by the processor 7954 in response to auser input 7958 or feedback elements 7960, may cause the motor controlcircuit 7946 to motivate the motor 7942 to generate at least onerotational motion to selectively move gear elements within the selectorgearbox assembly 7938 to selectively position one of the drivetrains7932, 7934, 7936 into engagement with the input drive component of thesecond motor 7944. Furthermore, the processor 7954 can be incommunication with the motor control circuit 7948. The memory 7956 alsomay store program instructions, which when executed by the processor7954 in response to a user input 7958, may cause the motor controlcircuit 7948 to motivate the motor 7944 to generate at least onerotational motion to drive the drivetrain engaged with the input drivecomponent of the second motor 7948, for example.

The controller 7952 and/or other controllers of the present disclosuremay be implemented using integrated and/or discrete hardware elements,software elements, and/or a combination of both. Examples of integratedhardware elements may include processors, microprocessors,microcontrollers, integrated circuits, ASICs, PLDs, DSPs, FPGAs, logicgates, registers, semiconductor devices, chips, microchips, chip sets,microcontrollers, system on a chip (SoC), and/or single in-line package(SIP). Examples of discrete hardware elements may include circuitsand/or circuit elements such as logic gates, field effect transistors,bipolar transistors, resistors, capacitors, inductors, and/or relays. Incertain instances, the controller 7952 may include a hybrid circuitcomprising discrete and integrated circuit elements or components on oneor more substrates, for example.

In certain instances, the controller 7952 and/or other controllers ofthe present disclosure may be an LM 4F230H5QR, available from TexasInstruments, for example. In certain instances, the Texas InstrumentsLM4F230H5QR is an ARM Cortex-M4F Processor Core comprising on-chipmemory of 256 KB single-cycle flash memory, or other non-volatilememory, up to 40 MHz, a prefetch buffer to improve performance above 40MHz, a 32 KB single-cycle SRAM, internal ROM loaded with StellarisWare®software, 2 KB EEPROM, one or more PWM modules, one or more QEI analog,one or more 12-bit ADC with 12 analog input channels, among otherfeatures that are readily available. Other microcontrollers may bereadily substituted for use with the present disclosure. Accordingly,the present disclosure should not be limited in this context.

In various instances, one or more of the various steps described hereincan be performed by a finite state machine comprising either acombinational logic circuit or a sequential logic circuit, where eitherthe combinational logic circuit or the sequential logic circuit iscoupled to at least one memory circuit. The at least one memory circuitstores a current state of the finite state machine. The combinational orsequential logic circuit is configured to cause the finite state machineto the steps. The sequential logic circuit may be synchronous orasynchronous. In other instances, one or more of the various stepsdescribed herein can be performed by a circuit that includes acombination of the processor 7958 and the finite state machine, forexample.

In various instances, it can be advantageous to be able to assess thestate of the functionality of a surgical instrument to ensure its properfunction. It is possible, for example, for the drive mechanism, asexplained above, which is configured to include various motors,drivetrains, and/or gear components in order to perform the variousoperations of the surgical instrument, to wear out over time. This canoccur through normal use, and in some instances the drive mechanism canwear out faster due to abuse conditions. In certain instances, asurgical instrument can be configured to perform self-assessments todetermine the state, e.g. health, of the drive mechanism and it variouscomponents.

For example, the self-assessment can be used to determine when thesurgical instrument is capable of performing its function before are-sterilization or when some of the components should be replacedand/or repaired. Assessment of the drive mechanism and its components,including but not limited to the rotation drivetrain 7932, the closuredrivetrain 7934, and/or the firing drivetrain 7936, can be accomplishedin a variety of ways. The magnitude of deviation from a predictedperformance can be used to determine the likelihood of a sensed failureand the severity of such failure. Several metrics can be used including:Periodic analysis of repeatably predictable events, Peaks or drops thatexceed an expected threshold, and width of the failure.

In various instances, a signature waveform of a properly functioningdrive mechanism or one or more of its components can be employed toassess the state of the drive mechanism or the one or more of itscomponents. One or more vibration sensors can be arranged with respectto a properly functioning drive mechanism or one or more of itscomponents to record various vibrations that occur during operation ofthe properly functioning drive mechanism or the one or more of itscomponents. The recorded vibrations can be employed to create thesignature waveform. Future waveforms can be compared against thesignature waveform to assess the state of the drive mechanism and itscomponents.

Still referring to FIG. 41, the surgical instrument 7930 includes adrivetrain failure detection module 7962 configured to record andanalyze one or more acoustic outputs of one or more of the drivetrains7932, 7934, 7936. The processor 7954 can be in communication with orotherwise control the module 7962. As described below in greater detail,the module 7962 can be embodied as various means, such as circuitry,hardware, a computer program product comprising a computer readablemedium (for example, the memory 7956) storing computer readable programinstructions that are executable by a processing device (for example,the processor 7954), or some combination thereof. In some aspects, theprocessor 36 can include, or otherwise control the module 7962.

FIG. 42 is an alternative system 132000 for controlling the frequency ofan ultrasonic electromechanical system 132002 and detecting theimpedance thereof, in accordance with at least one aspect of the presentdisclosure. The system 132000 may be incorporated into a generator. Aprocessor 132004 coupled to a memory 132026 programs a programmablecounter 132006 to tune to the output frequency f_(o) of the ultrasonicelectromechanical system 132002. The input frequency is generated by acrystal oscillator 132008 and is input into a fixed counter 132010 toscale the frequency to a suitable value. The outputs of the fixedcounter 132010 and the programmable counter 132006 are applied to aphase/frequency detector 132012. The output of the phase/frequencydetector 132012 is applied to an amplifier/active filter circuit 132014to generate a tuning voltage V_(t) that is applied to a voltagecontrolled oscillator 132016 (VCO). The VCO 132016 applies the outputfrequency f_(o) to an ultrasonic transducer portion of the ultrasonicelectromechanical system 132002, shown here modeled as an equivalentelectrical circuit. The voltage and current signals applied to theultrasonic transducer are monitored by a voltage sensor 132018 and acurrent sensor 132020.

The outputs of the voltage and current sensors 132018, 13020 are appliedto another phase/frequency detector 132022 to determine the phase anglebetween the voltage and current as measured by the voltage and currentsensors 132018, 13020. The output of the phase/frequency detector 132022is applied to one channel of a high speed analog to digital converter132024 (ADC) and is provided to the processor 132004 therethrough.Optionally, the outputs of the voltage and current sensors 132018,132020 may be applied to respective channels of the two-channel ADC132024 and provided to the processor 132004 for zero crossing, FFT, orother algorithm described herein for determining the phase angle betweenthe voltage and current signals applied to the ultrasonicelectromechanical system 132002.

Optionally the tuning voltage V_(t), which is proportional to the outputfrequency f_(o), may be fed back to the processor 132004 via the ADC132024. This provides the processor 132004 with a feedback signalproportional to the output frequency f_(o) and can use this feedback toadjust and control the output frequency f_(o).

Temperature Inference

FIGS. 43A-43B are graphical representations 133000, 133010 of compleximpedance spectra of the same ultrasonic device with a cold (roomtemperature) and hot ultrasonic blade, in accordance with at least oneaspect of the present disclosure. As used herein, a cold ultrasonicblade refers to an ultrasonic blade at room temperature and a hotultrasonic blade refers to an ultrasonic blade after it is frictionallyheated in use. FIG. 43A is a graphical representation 133000 ofimpedance phase angle φ as a function of resonant frequency f_(o) of thesame ultrasonic device with a cold and hot ultrasonic blade and FIG. 43Bis a graphical representation 133010 of impedance magnitude |Z| as afunction of resonant frequency f_(o) of the same ultrasonic device witha cold and hot ultrasonic blade. The impedance phase angle φ andimpedance magnitude |Z| are at a minimum at the resonant frequencyf_(o).

The ultrasonic transducer impedance Z_(g)(t) can be measured as theratio of the drive signal generator voltage V_(g)(t) and currentI_(g)(t) drive signals:

${Z_{g}(t)} = \frac{V_{g}(t)}{I_{g}(t)}$

As shown in FIG. 43A, when the ultrasonic blade is cold, e.g., at roomtemperature and not frictionally heated, the electromechanical resonantfrequency f, of the ultrasonic device is approximately 55,500 Hz and theexcitation frequency of the ultrasonic transducer is set to 55,500 Hz.Thus, when the ultrasonic transducer is excited at the electromechanicalresonant frequency f_(o) and the ultrasonic blade is cold the phaseangle φ is at minimum or approximately 0 Rad as indicated by the coldblade plot 133002. As shown in FIG. 43B, when the ultrasonic blade iscold and the ultrasonic transducer is excited at the electromechanicalresonant frequency f_(o), the impedance magnitude |Z| is 800 Ω, e.g.,the impedance magnitude |Z| is at a minimum impedance, and the drivesignal amplitude is at a maximum due to the series resonance equivalentcircuit of the ultrasonic electromechanical system as depicted in FIG.25.

With reference now back to FIGS. 43A and 43B, when the ultrasonictransducer is driven by generator voltage V_(g)(t) and generator currentI_(g)(t) signals at the electromechanical resonant frequency f_(o) of55,500 Hz, the phase angle φ between the generator voltage V_(g)(t) andgenerator current I_(g)(t) signals is zero, the impedance magnitude |Z|is at a minimum impedance, e.g., 800 Ω, and the signal amplitude is at apeak or maximum due to the series resonance equivalent circuit of theultrasonic electromechanical system. As the temperature of theultrasonic blade increases, due to frictional heat generated in use, theelectromechanical resonant frequency f_(o)′ of the ultrasonic devicedecreases. Since the ultrasonic transducer is still driven by generatorvoltage V_(g)(t) and generator current I_(g)(t) signals at the previous(cold blade) electromechanical resonant frequency f_(o) of 55,500 Hz,the ultrasonic device operates off-resonance f_(o)′ causing a shift inthe phase angle φ between the generator voltage V_(g)(t) and generatorcurrent I_(g)(t) signals. There is also an increase in impedancemagnitude |Z| and a drop in peak magnitude of the drive signal relativeto the previous (cold blade) electromechanical resonant frequency of55,500 Hz. Accordingly, the temperature of the ultrasonic blade may beinferred by measuring the phase angle φ between the generator voltageV_(g)(t) and the generator current I_(g)(t) signals as theelectromechanical resonant frequency f_(o) changes due to the changes intemperature of the ultrasonic blade.

As previously described, an electromechanical ultrasonic system includesan ultrasonic transducer, a waveguide, and an ultrasonic blade. Aspreviously discussed, the ultrasonic transducer may be modeled as anequivalent series resonant circuit (see FIG. 25) comprising first branchhaving a static capacitance and a second “motional” branch having aserially connected inductance, resistance and capacitance that definethe electromechanical properties of a resonator. The electromechanicalultrasonic system has an initial electromechanical resonant frequencydefined by the physical properties of the ultrasonic transducer, thewaveguide, and the ultrasonic blade. The ultrasonic transducer isexcited by an alternating voltage V_(g)(t) and current I_(g)(t) signalat a frequency equal to the electromechanical resonant frequency, e.g.,the resonant frequency of the electromechanical ultrasonic system. Whenthe electromechanical ultrasonic system is excited at the resonantfrequency, the phase angle φ between the voltage V_(g)(t) and currentI_(g)(t) signals is zero.

Stated in another way, at resonance, the analogous inductive impedanceof the electromechanical ultrasonic system is equal to the analogouscapacitive impedance of the electromechanical ultrasonic system. As theultrasonic blade heats up, for example due to frictional engagement withtissue, the compliance of the ultrasonic blade (modeled as an analogouscapacitance) causes the resonant frequency of the electromechanicalultrasonic system to shift. In the present example, the resonantfrequency of the electromechanical ultrasonic system decreases as thetemperature of the ultrasonic blade increases. Thus, the analogousinductive impedance of the electromechanical ultrasonic system is nolonger equal to the analogous capacitive impedance of theelectromechanical ultrasonic system causing a mismatch between the drivefrequency and the new resonant frequency of the electromechanicalultrasonic system. Thus, with a hot ultrasonic blade, theelectromechanical ultrasonic system operates “off-resonance.” Themismatch between the drive frequency and the resonant frequency ismanifested as a phase angle φ between the voltage V_(g)(t) and currentI_(g)(t) signals applied to the ultrasonic transducer.

As previously discussed, the generator electronics can easily monitorthe phase angle cp between the voltage V_(g)(t) and current I_(g)(t)signals applied to the ultrasonic transducer. The phase angle φ may bedetermined through Fourier analysis, weighted least-squares estimation,Kalman filtering, space-vector-based techniques, zero-crossing method,Lissajous figures, three-voltmeter method, crossed-coil method, vectorvoltmeter and vector impedance methods, phase standard instruments,phase-locked loops, among other techniques previously described. Thegenerator can continuously monitor the phase angle 9 and adjust thedrive frequency until the phase angle φ goes to zero. At this point, thenew drive frequency is equal to the new resonant frequency of theelectromechanical ultrasonic system. The change in phase angle φ and/orgenerator drive frequency can be used as an indirect or inferredmeasurement of the temperature of the ultrasonic blade.

A variety of techniques are available to estimate temperature from thedata in these spectra. Most notably, a time variant, non-linear set ofstate space equations can be employed to model the dynamic relationshipbetween the temperature of the ultrasonic blade and the measuredimpedance

${Z_{g}(t)} = \frac{V_{g}(t)}{I_{g}(t)}$

across a range of generator drive frequencies, where the range ofgenerator drive frequencies is specific to device model.

Methods of Temperature Estimation

One aspect of estimating or inferring the temperature of an ultrasonicblade may include three steps. First, define a state space model oftemperature and frequency that is time and energy dependent. To modeltemperature as a function of frequency content, a set of non-linearstate space equations are used to model the relationship between theelectromechanical resonant frequency and the temperature of theultrasonic blade. Second, apply a Kalman filter to improve the accuracyof the temperature estimator and state space model over time. Third, astate estimator is provided in the feedback loop of the Kalman filter tocontrol the power applied to the ultrasonic transducer, and hence theultrasonic blade, to regulate the temperature of the ultrasonic blade.The three steps are described hereinbelow.

Step 1

The first step is to define a state space model of temperature andfrequency that is time and energy dependent. To model temperature as afunction of frequency content, a set of non-linear state space equationsare used to model the relationship between the electromechanicalresonant frequency and the temperature of the ultrasonic blade. In oneaspect, the state space model is given by:

$\begin{bmatrix}{\overset{.}{F}}_{n} \\\overset{.}{T}\end{bmatrix} = {f\left( {t,{T(t)},{F_{n}(t)},{E(t)}} \right)}$$\overset{.}{y} = {h\left( {t,{T(t)},{F_{n}(t)},{E(t)}} \right)}$

The state space model represents the rate of change of the naturalfrequency of the electromechanical ultrasonic system f′{dot over(F)}_(n), and the rate of change of the temperature {dot over (T)} ofthe ultrasonic blade with respect to natural frequency F_(n)(t),temperature T(t), energy E(t), and time t. {dot over (Y)} represents theobservability of variables that are measurable and observable such asthe natural frequency F_(n)(t) of the electromechanical ultrasonicsystem, the temperature T(t) of the ultrasonic blade, the energy E(t)applied to the ultrasonic blade, and time t. The temperature T(t) of theultrasonic blade is observable as an estimate.

Step 2

The second step is to apply a Kalman filter to improve temperatureestimator and state space model. FIG. 44 is a diagram of a Kalman filter133020 to improve the temperature estimator and state space model basedon impedance according to the equation:

${Z_{g}(t)} = \frac{V_{g}(t)}{I_{g}(t)}$

which represents the impedance across an ultrasonic transducer measuredat a variety of frequencies, in accordance with at least one aspect ofthe present disclosure.

The Kalman filter 133020 may be employed to improve the performance ofthe temperature estimate and allows for the augmentation of externalsensors, models, or prior information to improve temperature predictionin the midst of noisy data. The Kalman filter 133020 includes aregulator 133022 and a plant 133024. In control theory a plant 133024 isthe combination of process and actuator. A plant 133024 may be referredto with a transfer function which indicates the relation between aninput signal and the output signal of a system. The regulator 133022includes a state estimator 133026 and a controller K 133028. The stateregulator 133026 includes a feedback loop 133030. The state regulator133026 receives y, the output of the plant 133024, as an input and afeedback variable u. The state estimator 133026 is an internal feedbacksystem that converges to the true value of the state of the system. Theoutput of the state estimator 133026 is {circumflex over (x)} the fullfeedback control variable including F_(n)(t) of the electromechanicalultrasonic system, the estimate of the temperature T(t) of theultrasonic blade, the energy E(t) applied to the ultrasonic blade, thephase angle φ, and time t. The input into the controller K 133028 is{circumflex over (x)} and the output of the controller K 133028 u is fedback to the state estimator 133026 and t of the plant 133024.

Kalman filtering, also known as linear quadratic estimation (LQE), is analgorithm that uses a series of measurements observed over time,containing statistical noise and other inaccuracies, and producesestimates of unknown variables that tend to be more accurate than thosebased on a single measurement alone, by estimating a joint probabilitydistribution over the variables for each timeframe and thus calculatingthe maximum likelihood estimate of actual measurements. The algorithmworks in a two-step process. In a prediction step, the Kalman filter133020 produces estimates of the current state variables, along withtheir uncertainties. Once the outcome of the next measurement(necessarily corrupted with some amount of error, including randomnoise) is observed, these estimates are updated using a weightedaverage, with more weight being given to estimates with highercertainty. The algorithm is recursive and can run in real time, usingonly the present input measurements and the previously calculated stateand its uncertainty matrix; no additional past information is required.

The Kalman filter 133020 uses a dynamics model of the electromechanicalultrasonic system, known control inputs to that system, and multiplesequential measurements (observations) of the natural frequency andphase angle of the applied signals (e.g., magnitude and phase of theelectrical impedance of the ultrasonic transducer) to the ultrasonictransducer to form an estimate of the varying quantities of theelectromechanical ultrasonic system (its state) to predict thetemperature of the ultrasonic blade portion of the electromechanicalultrasonic system that is better than an estimate obtained using onlyone measurement alone. As such, the Kalman filter 133020 is an algorithmthat includes sensor and data fusion to provide the maximum likelihoodestimate of the temperature of the ultrasonic blade.

The Kalman filter 133020 deals effectively with uncertainty due to noisymeasurements of the applied signals to the ultrasonic transducer tomeasure the natural frequency and phase shift data and also dealseffectively with uncertainty due to random external factors. The Kalmanfilter 133020 produces an estimate of the state of the electromechanicalultrasonic system as an average of the predicted state of the system andof the new measurement using a weighted average. Weighted values providebetter (i.e., smaller) estimated uncertainty and are more “trustworthy”than unweighted values The weights may be calculated from thecovariance, a measure of the estimated uncertainty of the prediction ofthe system's state. The result of the weighted average is a new stateestimate that lies between the predicted and measured state, and has abetter estimated uncertainty than either alone. This process is repeatedat every time step, with the new estimate and its covariance informingthe prediction used in the following iteration. This recursive nature ofthe Kalman filter 133020 requires only the last “best guess,” ratherthan the entire history, of the state of the electromechanicalultrasonic system to calculate a new state.

The relative certainty of the measurements and current state estimate isan important consideration, and it is common to discuss the response ofthe filter in terms of the gain K of the Kalman filter 133020. TheKalman gain K is the relative weight given to the measurements andcurrent state estimate, and can be “tuned” to achieve particularperformance. With a high gain K, the Kalman filter 133020 places moreweight on the most recent measurements, and thus follows them moreresponsively. With a low gain K, the Kalman filter 133020 follows themodel predictions more closely. At the extremes, a high gain close toone will result in a more jumpy estimated trajectory, while low gainclose to zero will smooth out noise but decrease the responsiveness.

When performing the actual calculations for the Kalman filter 133020 (asdiscussed below), the state estimate and covariances are coded intomatrices to handle the multiple dimensions involved in a single set ofcalculations. This allows for a representation of linear relationshipsbetween different state variables (such as position, velocity, andacceleration) in any of the transition models or covariances. Using aKalman filter 133020 does not assume that the errors are Gaussian.However, the Kalman filter 133020 yields the exact conditionalprobability estimate in the special case that all errors areGaussian-distributed.

Step 3

The third step uses a state estimator 133026 in the feedback loop 133032of the Kalman filter 133020 for control of power applied to theultrasonic transducer, and hence the ultrasonic blade, to regulate thetemperature of the ultrasonic blade.

FIG. 45 is a graphical depiction 133040 of three probabilitydistributions employed by the state estimator 133026 of the Kalmanfilter 133020 shown in FIG. 44 to maximize estimates, in accordance withat least one aspect of the present disclosure. The probabilitydistributions include the prior probability distribution 133042, theprediction (state) probability distribution 133044, and the observationprobability distribution 133046. The three probability distributions133042, 133044, 1330467 are used in feedback control of power applied toan ultrasonic transducer to regulate temperature based on impedanceacross the ultrasonic transducer measured at a variety of frequencies,in accordance with at least one aspect of the present disclosure. Theestimator used in feedback control of power applied to an ultrasonictransducer to regulate temperature based on impedance is given by theexpression:

${Z_{g}(t)} = \frac{V_{g}(t)}{I_{g}(t)}$

which is the impedance across the ultrasonic transducer measured at avariety of frequencies, in accordance with at least one aspect of thepresent disclosure.

The prior probability distribution 133042 includes a state variancedefined by the expression:

(σ_(k) ⁻)²=σ_(k−1) ²+σ_(P) _(k) ²

The state variance (σ_(k) ^(k)) is used to predict the next state of thesystem, which is represented as the prediction (state) probabilitydistribution 133044. The observation probability distribution 133046 isthe probability distribution of the actual observation of the state ofthe system where the observation variance σ_(m) is used to define thegain, which is given by the following expression:

$K = \frac{\left( \sigma_{k}^{-} \right)^{2}}{\left( \sigma_{k}^{-} \right)^{2} + \sigma_{m}^{2}}$

Feedback Control

Power input is decreased to ensure that the temperature (as estimated bythe state estimator and of the Kalman filter) is controlled.

In one aspect, the initial proof of concept assumed a static, linearrelationship between the natural frequency of the electromechanicalultrasonic system and the temperature of the ultrasonic blade. Byreducing the power as a function of the natural frequency of theelectromechanical ultrasonic system (i.e., regulating temperature withfeedback control), the temperature of the ultrasonic blade tip could becontrolled directly. In this example, the temperature of the distal tipof the ultrasonic blade can be controlled to not exceed the meltingpoint of the Teflon pad.

FIG. 46A is a graphical representation 133050 of temperature versus timeof an ultrasonic device without temperature feedback control.Temperature (° C.) of the ultrasonic blade is shown along the verticalaxis and time (sec) is shown along the horizontal axis. The test wasconducted with a chamois located in the jaws of the ultrasonic device.One jaw is the ultrasonic blade and the other jaw is the clamp arm witha TEFLON pad. The ultrasonic blade was excited at the resonant frequencywhile in frictional engagement with the chamois clamped between theultrasonic blade and the clamp arm. Over time, the temperature (° C.) ofthe ultrasonic blade increases due to the frictional engagement with thechamois. Over time, the temperature profile 133052 of the ultrasonicblade increases until the chamois sample is cut after about 19.5 secondsat a temperature of 220° C. as indicated at point 133054. Withouttemperature feedback control, after cutting the chamois sample, thetemperature of the ultrasonic blade increases to a temperature wellabove the melting point of TEFLON ˜380° C. up to ˜490° C. At point133056 the temperature of the ultrasonic blade reaches a maximumtemperature of 490° C. until the TEFLON pad is completely melted. Thetemperature of the ultrasonic blade drops slightly from the peaktemperature at point 133056 after the pad is completely gone.

FIG. 46B is a plot of temperature versus time of an ultrasonic devicewith temperature feedback control, in accordance with at least oneaspect of the present disclosure. Temperature (° C.) of the ultrasonicblade is shown along the vertical axis and the time (sec) is shown alongthe horizontal axis. The test was conducted with a chamois samplelocated in the jaws of the ultrasonic device. One jaw is the ultrasonicblade and the other jaw is the clamp arm with a TEFLON pad. Theultrasonic blade was excited at the resonant frequency while infrictional engagement with the chamois clamped between the ultrasonicblade and the clamp arm pad. Over time, the temperature profile 133062of the ultrasonic blade increases until the chamois sample is cut afterabout 23 seconds at a temperature of 220° C. as indicated at point133064. With temperature feedback control, the temperature of theultrasonic blade increases up to a maximum temperature of about 380° C.,just below the melting point of TEFLON, as indicated at point 133066 andthen is lowered to an average of about 330° C. as indicated generally atregion 133068, thus preventing the TEFLON pad from melting.

Application of Smart Ultrasonic Blade Technology

When an ultrasonic blade is immersed in a fluid-filled surgical field,the ultrasonic blade cools down during activation rendering lesseffective for sealing and cutting tissue in contact therewith. Thecooling down of the ultrasonic blade may lead to longer activation timesand/or hemostasis issues because adequate heat is not delivered to thetissue. In order to overcome the cooling of the ultrasonic blade, moreenergy delivery may be required to shorten the transection times andachieve suitable hemostasis under these fluid immersion conditions.Using a frequency-temperature feedback control system, if the ultrasonicblade temperature is detected to, either start out below, or remainbelow a certain temperature for a certain period of time, the outputpower of the generator can be increased to compensate for cooling due toblood/saline/other fluid present in the surgical field.

Accordingly, the frequency-temperature feedback control system describedherein can improve the performance of an ultrasonic device especiallywhen the ultrasonic blade is located or immersed, partially or wholly,in a fluid-filled surgical field. The frequency-temperature feedbackcontrol system described herein minimizes long activation times and/orpotential issues with ultrasonic device performance in fluid-filledsurgical field.

As previously described, the temperature of the ultrasonic blade may beinferred by detecting the impedance of the ultrasonic transducer givenby the following expression:

${Z_{g}(t)} = \frac{V_{g}(t)}{I_{g}(t)}$

or equivalently, detecting the phase angle φ between the voltageV_(g)(t) and current I_(g)(t) signals applied to the ultrasonictransducer. The phase angle cp information also may be used to infer theconditions of the ultrasonic blade. As discussed with particularityherein, the phase angle φ changes as a function of the temperature ofthe ultrasonic blade. Therefore, the phase angle φ information may beemployed to control the temperature of the ultrasonic blade. This may bedone, for example, by reducing the power delivered to the ultrasonicblade when the ultrasonic blade runs too hot and increasing the powerdelivered to the ultrasonic blade when the ultrasonic blade runs toocold. FIGS. 47A-47B are graphical representations of temperaturefeedback control for adjusting ultrasonic power applied to an ultrasonictransducer when a sudden drop in temperature of an ultrasonic blade isdetected.

FIG. 47A is a graphical representation of ultrasonic power output 133070as a function of time, in accordance with at least one aspect of thepresent disclosure. Power output of the ultrasonic generator is shownalong the vertical axis and time (sec) is shown along the horizontalaxis. FIG. 47B is a graphical representation of ultrasonic bladetemperature 133080 as a function of time, in accordance with at leastone aspect of the present disclosure. Ultrasonic blade temperature isshown along the vertical axis and time (sec) is shown along thehorizontal axis. The temperature of the ultrasonic blade increases withthe application of constant power 133072 as shown in FIG. 47A. Duringuse, the temperature of the ultrasonic blade suddenly drops. This mayresult from a variety of conditions, however, during use, it may beinferred that the temperature of the ultrasonic blade drops when it isimmersed in a fluid-filled surgical field (e.g., blood, saline, water,etc.). At time t₀, the temperature of the ultrasonic blade drops belowthe desired minimum temperature 133082 and the frequency-temperaturefeedback control algorithm detects the drop in temperature and begins toincrease or “ramp up” the power as shown by the power ramp 133074delivered to the ultrasonic blade to start raising the temperature ofthe ultrasonic blade above the desired minimum temperature 133082.

With reference to FIGS. 47A and 47B, the ultrasonic generator is outputssubstantially constant power 133072 as long the temperature of theultrasonic blade remains above the desired minimum temperature 133082.At t₀, processor or control circuit in the generator or instrument orboth detects the drop in temperature of the ultrasonic blade below thedesired minimum temperature 133072 and initiates a frequency-temperaturefeedback control algorithm to raise the temperature of the ultrasonicblade above the minimum desired temperature 133082. Accordingly, thegenerator power begins to ramp 133074 at t₁ corresponding to thedetection of a sudden drop in the temperature of the ultrasonic blade att₀. Under the frequency-temperature feedback control algorithm, thepower continues to ramp 133074 until the temperature of the ultrasonicblade is above the desired minimum temperature 133082.

FIG. 48 is a logic flow diagram 133090 of a process depicting a controlprogram or a logic configuration to control the temperature of anultrasonic blade, in accordance with at least one aspect of the presentdisclosure. According to the process, the processor or control circuitof the generator or instrument or both executes one aspect of afrequency-temperature feedback control algorithm discussed in connectionwith FIGS. 47A and 47B to apply 133092 a power level to the ultrasonictransducer to achieve a desired temperature at the ultrasonic blade. Thegenerator monitors 133094 the phase angle φ between the voltage V_(g)(t)and current I_(g)(t) signals applied to drive the ultrasonic transducer.Based on the phase angle φ, the generator infers 133096 the temperatureof the ultrasonic blade using the techniques described herein inconnection with FIGS. 43A-45. The generator determines 133098 whetherthe temperature of the ultrasonic blade is below a desired minimumtemperature by comparing the inferred temperature of the ultrasonicblade to a predetermined desired temperature. The generator then adjuststhe power level applied to the ultrasonic transducer based on thecomparison. For example, the process continues along NO branch when thetemperature of the ultrasonic blade is at or above the desired minimumtemperature and continues along YES branch when the temperature of theultrasonic blade is below the desired minimum temperature. When thetemperature of the ultrasonic blade is below the desired minimumtemperature, the generator increases 133100 the power level to theultrasonic transducer, e.g., by increasing the voltage V_(g)(t) and/orcurrent I_(g)(t) signals, to raise the temperature of the ultrasonicblade and continues increasing the power level applied to the ultrasonictransducer until the temperature of the ultrasonic blade increases abovethe minimum desired temperature.

Adaptive Advanced Tissue Treatment Pad Saver Mode

FIG. 49 is a graphical representation 133110 of ultrasonic bladetemperature as a function of time during a vessel firing, in accordancewith at least one aspect of the present disclosure. A plot 133112 ofultrasonic blade temperature is graphed along the vertical axis as afunction of time along the horizontal axis. The frequency-temperaturefeedback control algorithm combines the temperature of the ultrasonicblade feedback control with the jaw sensing ability. Thefrequency-temperature feedback control algorithm provides optimalhemostasis balanced with device durability and can deliver energyintelligently for best sealing while protecting the clamp arm pad.

As shown in FIG. 49, the optimum temperature 133114 for vessel sealingis marked as a first target temperature T₁ and the optimum temperature133116 for “infinite” clamp arm pad life is marked as a second targettemperature T₂. The frequency-temperature feedback control algorithminfers the temperature of the ultrasonic blade and maintains thetemperature of the ultrasonic blade between the first and second targettemperature thresholds T₁ and T₂. The generator power output is thusdriven to achieve optimal ultrasonic blade temperatures for sealingvessels and prolonging the life of the clamp arm pad.

Initially, the temperature of the ultrasonic blade increases as theblade heats up and eventually exceeds the first target temperaturethreshold T₁. The frequency-temperature feedback control algorithm takesover to control the temperature of the blade to T₁ until the vesseltransection is completed 133118 at t₀ and the ultrasonic bladetemperature drops below the second target temperature threshold T₂. Aprocessor or control circuit of the generator or instrument or bothdetects when the ultrasonic blade contacts the clamp arm pad. Once thevessel transection is completed at t₀ and detected, thefrequency-temperature feedback control algorithm switches to controllingthe temperature of the ultrasonic blade to the second target thresholdT₂ to prolong the life of the clam arm pad. The optimal clamp arm padlife temperature for a TEFLON clamp arm pad is approximately 325° C. Inone aspect, the advanced tissue treatment can be announced to the userat a second activation tone.

FIG. 50 is a logic flow diagram 133120 of a process depicting a controlprogram or a logic configuration to control the temperature of anultrasonic blade between two temperature set points as depicted in FIG.49, in accordance with at least one aspect of the present disclosure.According to the process, the generator executes one aspect of thefrequency-temperature feedback control algorithm to apply 133122 a firstpower level to the ultrasonic transducer, e.g., by adjusting the voltageV_(g)(t) and/or the current I_(g)(t) signals applied to the ultrasonictransducer, to set the ultrasonic blade temperature to a first target T₁optimized for vessel sealing. As previously described, the generatormonitors 133124 the phase angle φ between the voltage V_(g)(t) andcurrent I_(g)(t) signals applied to the ultrasonic transducer and basedon the phase angle φ, the generator infers 133126 the temperature of theultrasonic blade using the techniques described herein in connectionwith FIGS. 43A-45. According to the frequency-temperature feedbackcontrol algorithm, a processor or control circuit of the generator orinstrument or both maintains the ultrasonic blade temperature at thefirst target temperature T₁ until the transection is completed. Thefrequency-temperature feedback control algorithm may be employed todetect the completion of the vessel transection process. The processoror control circuit of the generator or instrument or both determines133128 when the vessel transection is complete. The process continuesalong NO branch when the vessel transection is not complete andcontinues along YES branch when the vessel transection is complete.

When the vessel transection in not complete, the processor or controlcircuit of the generator or instrument or both determines 133130 if thetemperature of the ultrasonic blade is set at temperature T₁ optimizedfor vessel sealing and transecting. If the ultrasonic blade temperatureis set at T₁, the process continues along the YES branch and theprocessor or control circuit of the generator or instrument or bothcontinues to monitor 133124 the phase angle cp between the voltageV_(g)(t) and current I_(g)(t) signals applied to the ultrasonictransducer and based on the phase angle φ. If the ultrasonic bladetemperature is not set at T₁, the process continues along NO branch andthe processor or control circuit of the generator or instrument or bothcontinues to apply 133122 a first power level to the ultrasonictransducer.

When the vessel transection is complete, the processor or controlcircuit of the generator or instrument or both applies 133132 a secondpower level to the ultrasonic transducer to set the ultrasonic blade toa second target temperature T₂ optimized for preserving or extending thelife of the clamp arm pad. The processor or control circuit of thegenerator or instrument or both determines 133134 if the temperature ofthe ultrasonic blade is at set temperature T₂. If the temperature of theultrasonic blade is set at T2, the process completes 133136 the vesseltransection procedure.

Start Temperature of Blade

Knowing the temperature of the ultrasonic blade at the beginning of atransection can enable the generator to deliver the proper quantity ofpower to heat up the blade for a quick cut or if the blade is alreadyhot add only as much power as would be needed. This technique canachieve more consistent transection times and extend the life of theclam arm pad (e.g., a TEFLON clamp arm pad). Knowing the temperature ofthe ultrasonic blade at the beginning of the transection can enable thegenerator to deliver the right amount of power to the ultrasonictransducer to generate a desired amount of displacement of theultrasonic blade.

FIG. 51 is a logic flow diagram 133140 of a process depicting a controlprogram or a logic configuration to determine the initial temperature ofan ultrasonic blade, in accordance with at least one aspect of thepresent disclosure. To determine the initial temperature of anultrasonic blade, at the manufacturing plant, the resonant frequenciesof ultrasonic blades are measured at room temperature or at apredetermined ambient temperature. The baseline frequency values arerecorded and stored in a lookup table of the generator or instrument orboth. The baseline values are used to generate a transfer function. Atthe start of an ultrasonic transducer activation cycle, the generatormeasures 133142 the resonant frequency of the ultrasonic blade andcompares 133144 the measured resonant frequency to the baseline resonantfrequency value and determines the difference in frequency (Δt). The Δfis compared to the lookup table or transfer function for correctedultrasonic blade temperature. The resonant frequency of the ultrasonicblade may be determined by sweeping the frequency of the voltageV_(g)(t) and current I_(g)(t) signals applied to the ultrasonictransducer. The resonant frequency is that frequency at which the phaseangle φ voltage V_(g)(t) and current I_(g)(t) signals is zero asdescribed herein.

Once the resonant frequency of the ultrasonic blade is determined, theprocessor or control circuit of the generator or instrument or bothdetermines 133146 the initial temperature of the ultrasonic blade basedon the difference between the measured resonant frequency and thebaseline resonant frequency. The generator sets the power leveldelivered the ultrasonic transducer, e.g., by adjusting the voltageV_(g)(t) or current I_(g)(t) drive signals or both, to one of thefollowing values prior to activating the ultrasonic transducer.

The processor or control circuit of the generator or instrument or bothdetermines 133148 if the initial temperature of the ultrasonic blade islow. If the initial temperature of the ultrasonic blade is low, theprocess continues along YES branch and the processor or control circuitof the generator or instrument or both applies 133152 a high power levelto the ultrasonic transducer to increase the temperature of theultrasonic blade and completes 133156 the vessel transection procedure.

If the initial temperature of the ultrasonic blade is not low, theprocess continues along NO branch and the processor or control circuitof the generator or instrument or both determines 133150 if the initialtemperature of the ultrasonic blade is high. If the initial temperatureof the ultrasonic blade is high, the process proceeds along YES branchand the processor or control circuit of the generator or instrument orboth applies 133154 a low power level to the ultrasonic transducer todecrease the temperature of the ultrasonic blade and completes 133156the vessel transection procedure. If the initial temperature of theultrasonic blade is not high, the process continues along NO branch andthe processor or control circuit of the generator or instrument or bothcompletes 133156 the vessel transection.

Smart Blade Technology to Control Blade Instability

The temperature of an ultrasonic blade and the contents within the jawsof an ultrasonic end effector can be determined using thefrequency-temperature feedback control algorithms described herein. Thefrequency/temperature relationship of the ultrasonic blade is employedto control ultrasonic blade instability with temperature.

As described herein, there is a well-known relationship between thefrequency and temperature in ultrasonic blades. Some ultrasonic bladesexhibit displacement instability or modal instability in the presence ofincreasing temperature. This known relationship may be employed tointerpret when an ultrasonic blade is approaching instability and thenadjusting the power level driving the ultrasonic transducer (e.g., byadjusting the driving voltage V_(g)(t) or current I_(g)(t) signals, orboth, applied to the ultrasonic transducer) to modulate the temperatureof the ultrasonic blade to prevent instability of the ultrasonic blade.

FIG. 52 is a logic flow diagram 133160 of a process depicting a controlprogram or a logic configuration to determine when an ultrasonic bladeis approaching instability and then adjusting the power to theultrasonic transducer to prevent instability of the ultrasonictransducer, in accordance with at least one aspect of the presentdisclosure. The frequency/temperature relationship of an ultrasonicblade that exhibits a displacement or modal instability is mapped bysweeping the frequency of the drive voltage V_(g)(t) or current I_(g)(t)signals, or both, over the temperature of the ultrasonic blade andrecording the results. A function or relationship is developed that canbe used/interpreted by a control algorithm executed by the generator.Trigger points can be established using the relationship to notify thegenerator that an ultrasonic blade is approaching the known bladeinstability. The generator executes a frequency-temperature feedbackcontrol algorithm processing function and closed loop response such thatthe driving power level is reduced (e.g., by lowering the drivingvoltage V_(g)(t) or current I_(g)(t), or both, applied to the ultrasonictransducer) to modulate the temperature of the ultrasonic blade at orbelow the trigger point to prevent a given blade from reachinginstability.

Advantages include simplification of ultrasonic blade configurationssuch that the instability characteristics of the ultrasonic blade do notneed to be designed out and can be compensated using the presentinstability control technique. The present instability control techniquealso enables new ultrasonic blade geometries and can improve stressprofile in heated ultrasonic blades. Additionally, ultrasonic blades canbe configured to diminish performance of the ultrasonic blade if usedwith generators that do not employ this technique.

In accordance with the process depicted by the logic flow diagram133160, the processor or control circuit of the generator or instrumentor both monitors 133162 the phase angle cp between the voltage V_(g)(t)and current I_(g)(t) signals applied to the ultrasonic transducer. Theprocessor or control circuit of the generator or instrument or bothinfers 133164 the temperature of the ultrasonic blade based on the phaseangle cp between the voltage V_(g)(t) and current I_(g)(t) signalsapplied to the ultrasonic transducer. The processor or control circuitof the generator or instrument or both compares 133166 the inferredtemperature of the ultrasonic blade to an ultrasonic blade instabilitytrigger point threshold. The processor or control circuit of thegenerator or instrument or both determines 133168 whether the ultrasonicblade is approaching instability. If not, the process proceed along theNO branch and monitors 133162 the phase angle φ, infers 133164 thetemperature of the ultrasonic blade, and compares 133166 the inferredtemperature of the ultrasonic blade to an ultrasonic blade instabilitytrigger point threshold until the ultrasonic blade approachesinstability. The process then proceeds along the YES branch and theprocessor or control circuit of the generator or instrument or bothadjusts 133170 the power level applied to the ultrasonic transducer tomodulate the temperature of the ultrasonic blade.

Ultrasonic Sealing Algorithm with Temperature Control

Ultrasonic sealing algorithms for ultrasonic blade temperature controlcan be employed to improve hemostasis utilizing a frequency-temperaturefeedback control algorithm described herein to exploit thefrequency/temperature relationship of ultrasonic blades.

In one aspect, a frequency-temperature feedback control algorithm may beemployed to alter the power level applied to the ultrasonic transducerbased on measured resonant frequency (using spectroscopy) which relatesto temperature, as described in various aspects of the presentdisclosure. In one aspect, the frequency-temperature feedback controlalgorithm may be activated by an energy button on the ultrasonicinstrument.

It is known that optimal tissue effects may be obtained by increasingthe power level driving the ultrasonic transducer (e.g., by increasingthe driving voltage V_(g)(t) or current I_(g)(t), or both, applied tothe ultrasonic transducer) early on in the sealing cycle to rapidly heatand desiccate the tissue, then lowering the power level driving theultrasonic transducer (e.g., by lowering the driving voltage V_(g)(t) orcurrent I_(g)(t), or both, applied to the ultrasonic transducer) toslowly allow the final seal to form. In one aspect, afrequency-temperature feedback control algorithm according to thepresent disclosure sets a limit on the temperature threshold that thetissue can reach as the tissue heats up during the higher power levelstage and then reduces the power level to control the temperature of theultrasonic blade based on the melting point of the clamp jaw pad (e.g.,TEFLON) to complete the seal. The control algorithm can be implementedby activating an energy button on the instrument for a moreresponsive/adaptive sealing to reduce more the complexity of thehemostasis algorithm.

FIG. 53 is a logic flow diagram 133180 of a process depicting a controlprogram or a logic configuration to provide ultrasonic sealing withtemperature control, in accordance with at least one aspect of thepresent disclosure. According to the control algorithm, the processor orcontrol circuit of the generator or instrument or both activates 133182ultrasonic blade sensing using spectroscopy (e.g., smart blade) andmeasures 133184 the resonant frequency of the ultrasonic blade (e.g.,the resonant frequency of the ultrasonic electromechanical system) todetermine the temperature of the ultrasonic blade using afrequency-temperature feedback control algorithm (spectroscopy) asdescribed herein. As previously described, the resonant frequency of theultrasonic electromechanical system is mapped to obtain the temperatureof the ultrasonic blade as a function of resonant frequency of theelectromechanical ultrasonic system.

A first desired resonant frequency f_(x) of the ultrasonicelectromechanical system corresponds to a first desired temperature Z°of the ultrasonic blade. In one aspect, the first desired ultrasonicblade temperature Z° is an optimal temperature (e.g., 450° C.) fortissue coagulation. A second desired frequency f_(y) of the ultrasonicelectromechanical system corresponds to a second desired temperature ZZ°of the ultrasonic blade. In one aspect, the second desired ultrasonicblade temperature ZZ° is a temperature of 330° C., which is below themelting point of the clamp arm pad, which is approximately 380° C. forTEFLON.

The processor or control circuit of the generator or instrument or bothcompares 133186 the measured resonant frequency of the ultrasonicelectromechanical system to the first desired frequency f_(x). In otherwords, the process determines whether the temperature of the ultrasonicblade is less than the temperature for optimal tissue coagulation. Ifthe measured resonant frequency of the ultrasonic electromechanicalsystem is less than the first desired frequency f_(x), the processcontinues along the NO branch and the processor or control circuit ofthe generator or instrument or both increases 133188 the power levelapplied to the ultrasonic transducer to increase the temperature of theultrasonic blade until the measured resonant frequency of the ultrasonicelectromechanical system exceeds the first desired frequency f_(x). Inwhich case, the tissue coagulation process is completed and the processcontrols the temperature of the ultrasonic blade to the second desiredtemperature corresponding to the second desired frequency f_(y).

The process continues along the YES branch and the processor or controlcircuit of the generator or instrument or both decreases 133190 thepower level applied to the ultrasonic transducer to decrease thetemperature of the ultrasonic blade. The processor or control circuit ofthe generator or instrument or both measures 133192 the resonantfrequency of the ultrasonic electromechanical system and compares themeasured resonant frequency to the second desired frequency f_(y). Ifthe measured resonant frequency is not less than the second desiredfrequency f_(y), the processor or control circuit of the generator orinstrument or both decreases 133190 the ultrasonic power level until themeasured resonant frequency is less than the second desired frequencyf_(y). The frequency-temperature feedback control algorithm to maintainthe measured resonant frequency of the ultrasonic electromechanicalsystem below the second desired frequency f_(y), e.g., the temperatureof the ultrasonic blade is less than the temperature of the meltingpoint of the clamp arm pad then, the generator executes the increasesthe power level applied to the ultrasonic transducer to increase thetemperature of the ultrasonic blade until the tissue transection processis complete 133196.

FIG. 54 is a graphical representation 133200 of ultrasonic transducercurrent and ultrasonic blade temperature as a function of time, inaccordance with at least one aspect of the present disclosure. FIG. 54illustrates the results of the application of the frequency-temperaturefeedback control algorithm described in FIG. 53. The graphicalrepresentation 133200 depicts a first plot 133202 of ultrasonic bladetemperature as a function of time with respect to a second plot 133204of ultrasonic transducer current I_(g)(t) as a function of time. Asshown, the transducer I_(g)(t) is maintained constant until theultrasonic blade temperature reaches 450°, which is an optimalcoagulation temperature. Once the ultrasonic blade temperature reaches450°, the frequency-temperature feedback control algorithm decrease thetransducer current I_(g)(t) until the temperature of the ultrasonicblade drops to below 330°, which is below the melting point of a TEFLONpad, for example.

Tissue Type Identification or Parameterization

In various aspects, a surgical instrument (e.g., an ultrasonic surgicalinstrument) is configured to identify or parameterize the tissue graspedby the end effector and adjust various operational parameters of thesurgical instrument accordingly. The identification or parameterizationof the tissue can include the tissue type (e.g., the physiologicaltissue type), physical characteristics or properties of the tissue, thecomposition of the tissue, the location of the tissue within or relativeto the end effector, and so on. In one example discussed in greaterdetail below, the ultrasonic surgical instrument is configured to tunethe displacement amplitude of the distal tip of the ultrasonic bladeaccording to the collagen/elastin ratio of the tissue detected in thejaws of the end effector. As previously discussed, an ultrasonicinstrument comprises an ultrasonic transducer acoustically coupled to anultrasonic blade via an ultrasonic waveguide. The displacement of theultrasonic blade is a function of the electrical power applied to theultrasonic transducer and, accordingly, the electrical power supplied tothe ultrasonic transducer can be modulated according to the detectedcollagen/elastin ratio of the tissue. In another example discussed ingreater detail below, the force exerted by the clamp arm on the tissuecan be modulated according to the location of the tissue relative to theend effector. Various techniques for identifying or parameterizing thetissue are described herein and further details can be found in, forexample, U.S. Provisional Patent Application No. 62/692,768, titledSMART ENERGY DEVICES, filed on Jun. 30, 2018, the disclosure of which isherein incorporated by reference in its entirety.

Determining Tissue Location via Impedance Change

Referring back to FIG. 23, there is illustrated an end effector 1122comprising an ultrasonic blade 1128 and a clamp arm 1140, in accordancewith at least one aspect of the present disclosure. FIG. 55 is a bottomview of an ultrasonic end effector 1122 showing a clamp arm 1140 andultrasonic blade 1128 and delineating tissue positioning within theultrasonic end effector 1122, in accordance with at least one aspect ofthe present disclosure. The positioning of the tissue between the clamparm 1140 and ultrasonic blade 1128 can be delineated according to theregion or zone in which the tissue is located, such as a distal region130420 and a proximal region 130422.

With reference now to FIGS. 23 and 55, as described herein, theultrasonic end effector 1122 grasps tissue between the ultrasonic blade1128 and clamp arm 1140. Once tissue is grasped, the ultrasonicgenerator (e.g., the generator 1100 described in connection with FIG.22) may be activated to apply power to the ultrasonic transducer, whichis acoustically coupled to the ultrasonic blade 1128 via an ultrasonicwaveguide. The power applied to the ultrasonic transducer may be in atherapeutic or non-therapeutic range of energy levels. In anon-therapeutic range of applied power, the resulting displacement ofthe ultrasonic blade 1128 does not effect, or minimally effects, thegrasped tissue so as not to coagulate or cut the tissue. Thenon-therapeutic excitation may be particularly useful for determiningthe impedance of the ultrasonic transducer, which will vary based on avariety of conditions present at the end effector 1122, including, forexample, tissue type, tissue location within the end effector, ratio ofdifferent tissue types, and temperature of the ultrasonic blade, amongother conditions. A variety of these conditions are described herein.The impedance of the ultrasonic transducer is given by

${{Z_{g}(t)} = \frac{V_{g}(t)}{I_{g}(t)}},$

as described herein. Once the conditions at the ultrasonic end effector1122 are determined using non-therapeutic ultrasonic energy levels,therapeutic ultrasonic energy may be applied based on the determined endeffector 1122 conditions to optimize the tissue treatment, effectiveseal, transection, and duration, among other variables associated with aparticular surgical procedure. Therapeutic energy is sufficient tocoagulate and cut tissue.

In one aspect, the present disclosure provides a control process, suchas an algorithm, to determine the thickness and type of tissue locatedwithin the jaws (i.e., between the clamp arm 1140 and the ultrasonicblade 1128) of an ultrasonic end effector 1122 as shown in FIGS. 23 and55. Additional detail regarding detecting various states and propertiesof objects grasped by an end effector 1122 are discussed below under theheading DETERMINING JAW STATE and in U.S. Provisional Patent ApplicationNo. 62/692,768, titled SMART ENERGY DEVICES.

FIG. 56 is a graphical representation 130000 depicting change inultrasonic transducer impedance as a function tissue location within theultrasonic end effector 1122 over a range of predetermined ultrasonicgenerator power level increases, in accordance with at least one aspectof the present disclosure. The horizontal axis 130004 represents tissuelocation and the vertical axis 130002 represents transducer impedance(Ω). Various limits along the horizontal axis 130004, such as a first orproximal limit 130010 and a second or distal limit 130012, can delineateor correspond to different positions of the tissue grasped within theultrasonic end effector 1122. The delineation of proximal and distaltissue locations is shown schematically in FIG. 55 (i.e., proximalportion 130422 and distal portion 130420). The plots 130006, 130008represent the change in transducer impedance Ω as the power applied tothe ultrasonic transducer is varied from a minimum or firstnon-therapeutic power level L₁ to a maximum or second non-therapeuticpower level L₂. The larger the change in transducer impedance Ω is, thecloser the resulting plot will be to the distal limit 130012.Accordingly, the location of the tissue corresponds to the position ofthe resulting plot relative to the various limits (e.g., the proximallimit 130010 and the distal limit 130012). In the first plot 130006, δ₁represents the change in transducer impedance when tissue is located atthe proximal portion 130422 of the end effector 1122. This can be seenfrom the fact that the first plot 130006 does not exceed the proximallimit 130010. In the second plot 130008, δ₂ represents the change intransducer impedance when tissue is located at the distal end 130012 ofthe end effector 1122. This can be seen from the fact that the firstplot 130006 exceeds the proximal limit 130010 and/or is located near tothe distal limit 130012. As indicated by the plots 130006, 130008, δ₂ ismuch greater than δ₁.

When applying power (voltage and current) to the ultrasonic transducerto activate the ultrasonic blade 1128 in the non-therapeutic range (forexample, power that is not sufficient for cutting or coagulatingtissue), the resulting measured transducer impedance (Ω) is a usefulindicator of the position of tissue within the jaw of the end effector1122, whether at the distal end 130420 or proximal end 130422 of theultrasonic blade 1128 as shown in FIG. 55. The location of the tissuewithin the end effector 1122 can be determined based on the change intransducer impedance Ω as the non-therapeutic power level applied to theultrasonic transducer is varied from a minimum power level (e.g., L₁) toa maximum power level (e.g., L₂). In some aspects, the non-therapeuticpower level(s) applied to the ultrasonic transducer can cause theultrasonic blade 1128 to oscillate at a sensing amplitude or below theminimum therapeutic amplitude (e.g., less than or equal to 35 μm at thedistal and/or proximal end of the ultrasonic blade 1128). Calculation ofimpedance is discussed previously in this disclosure. A measure of thefirst transducer impedance Z₁ is taken when a first power level L₁ isapplied, which provides an initial measurement, and a subsequent measureof impedance Z₂ is taken again when the applied power is increased to asecond power level L₂. In one aspect, the first power level L₁=0.2 A andthe second power level L₂=0.4 A or twice the first power level L₁, whilethe voltage is maintained constant. The resulting longitudinaldisplacement amplitude of the ultrasonic blade 1128, based on theapplied power level, provides an indication of tissue location withinthe jaws of the end effector 1122. In one example implementation, thefirst power level L₁ produces a longitudinal displacement amplitude of35 μm at the distal end 130420 and 15 μm at the proximal end 130422.Further in this example, the second power level L₂ produces alongitudinal amplitude of 70 μm at the distal end 130420 and 35 μm atthe proximal end 130422. An algorithm calculates the difference intransducer impedance δ between the first and second measurements to findthe change in impedance ΔZ_(g)(t). The change in impedance δ is plottedagainst tissue location and shows that a higher change in impedancerepresents tissue location distributed at the distal end 130012 and alower change in impedance represents tissue location distributed at theproximal end 130010 of the end effector 1122. In sum, if there is alarge change in impedance as the power level is increased from L₁ to L₂,then the tissue is distally positioned only within the end effector1122; conversely, if there is only a small change in impedance as thepower level is increased from L₁ to L₂, then the tissue is moredistributed within the end effector 1122.

FIG. 57 is a graphical representation 130050 depicting change inultrasonic transducer impedance as a function of time relative to thelocation of tissue within the ultrasonic end effector, in accordancewith at least one aspect of the present disclosure. The horizontal axis130054 represents time (t) and the vertical axis 130052 representschange in transducer impedance (δ) between the first and secondmeasurements. The plots 130060, 130066 depict the change in transducerimpedance (δ) versus time (t), relative to the proximal and distallocation of tissue within the bite of the clamp arm 1140. For proximaland distal tissue location, a clamp arm 1140 force is applied to holdthe tissue in the ultrasonic end effector 1122 and a delay period isapplied before a first, low-power level is applied and the transducerimpedance is measured. Subsequently, the system applies a second, higherpower level and measures the impedance again. It will be appreciatedthat both the first and second power levels applied to the ultrasonictransducer are non-therapeutic power levels. The algorithm executed by aprocessor or control circuit portion of the generator, or the surgicalinstrument, (e.g., the processor 902 in FIG. 21 or the control circuit760 in FIG. 18) calculates the difference in transducer impedance (δ)between the first power level and the second power level for theproximal and distal tissue locations. As shown in relation to the firstplot 130060, if the difference in transducer impedance (δ) below a firstthreshold 130056, the algorithm determines that the tissue is located inthe proximal portion 130422 of the end effector 1122. In the first plot130060, the difference in the transducer impedance between themeasurements increases 130062 over time until it plateaus or maintains130064 below the first threshold 130056. As shown in relation to thefirst plot 130066, if the difference in transducer impedance (δ) isabove a second threshold 130058, the algorithm determines that thetissue is located in the distal portion 130420 of the of the endeffector 1122. In the second plot 130066, the difference in thetransducer impedance between the measurements increases 130068 over timeuntil it plateaus or maintains 130070 above the second threshold 130058.If the difference in transducer impedance (δ) is between the first andsecond thresholds 130056, 130058, the algorithm determines that thetissue is located in the middle portion 130424 of the end effector 1122,e.g., between the proximal and distal portions of the end effector.

FIG. 58 is a logic flow diagram of a process 130100 depicting a controlprogram or a logic configuration to identify operation in thenon-therapeutic range of power applied to the instrument in order todetermine tissue positioning, in accordance with at least one aspect ofthe present disclosure. The process 130100 can be executed by aprocessor or control circuit of a surgical instrument, such as thecontrol circuit 760 of FIG. 18, or a generator, such as the processor902 of FIG. 21. For conciseness, the process 130100 will be described asbeing executed by a processor, but it should be understood that thefollowing description encompasses the aforementioned variations.

In accordance with one aspect of the process 130100, a processor appliesa control signal to close the clamp arm 1140 to capture the tissuebetween the clamp arm 1140 and the ultrasonic blade 1128. After theclamp arm 1140 closes onto the tissue, the processor waits for apredetermined delay period to allow the tissue to relax and give up somemoisture content. After the delay period, the processor sets 130102 thepower level applied to ultrasonic transducer to a first non-therapeuticpower level. Optionally, one aspect of the process 130100 includes afeedback control can be used to verify that the first power is set belowa therapeutic power level. In this aspect, the processor determines130106 whether the first power level is less than a therapeutic powerlevel. If the first power level is not less than a therapeutic powerlevel, the process 130100 continues along the NO branch and theprocessor decreases 130108 the applied power and loops until the firstpower level is less than a therapeutic power level. The process 130100then continues along the YES branch and the processor measures 130110 afirst impedance Z_(g1)(t) of the ultrasonic transducer corresponding tothe first power level. The processor then sets 130112 the power levelapplied to ultrasonic transducer to a second non-therapeutic powerlevel, where the second power is greater than the first power level andis below a therapeutic power level. Again, optionally, a feedbackcontrol can be used to verify that the second power level is not onlygreater than the first power level but also is below a therapeutic powerlevel. In this aspect, the processor determines 130114 whether thesecond power level is less than a therapeutic power level. If the secondpower is greater than a therapeutic power level, the process 130100continues along the NO branch and the processor decreases 130108 thesecond power level and loops until it is below a therapeutic power levelthreshold. The process 130100 then continues along the YES branch andthe processor measures 130116 a second impedance Z_(g2)(t) of theultrasonic transducer corresponding to the second power level. Theimpedance of the ultrasonic transducer can be measured using a varietyof techniques as discussed herein. The processor then calculates 130118the difference in transducer impedance between the applied first andsecond power levels:

δ=Z _(g2)(t)−Z _(g1)(t).

The processor then provides 130120 an indication of the tissue positionto the user. The processor can indicate the tissue position via anoutput device of a surgical instrument (e.g., visual feedback devices,such as the display depicted in FIG. 31, audio feedback devices, and/ortactile feedback devices), a display 135 (FIG. 3), or other outputdevice of a surgical hub 106 communicably connected to the surgicalinstrument and/or an output device 2140 (FIG. 27B) of a generator 1100(e.g., visual feedback devices, audio feedback devices, and/or tactilefeedback devices).

The processor compares the difference in transducer impedance to a firstand second threshold where, as shown in FIG. 57, if the difference intransducer impedance (δ) below a first threshold 130056, the algorithmdetermines that the tissue is located in the proximal portion 130422 ofthe end effector 1122 and if the difference in transducer impedance (δ)is above a second threshold 130058, the algorithm determines that thetissue is located in the distal portion 130420 of the of the endeffector 1122. If the difference in transducer impedance (δ) is betweenthe first and second thresholds 130056, 130058, the algorithm determinesthat the tissue is located in the middle portion 130424 of the endeffector 1122, e.g., between the proximal and distal portions 130422,130420 of the end effector 1122. According to the described process, theimpedance of the ultrasonic transducer can be employed to differentiatewhat percent of tissue is located in a distal, proximal, or intermediatelocation of the end effector 1122 and then apply a suitable therapeuticpower level.

Switchless Mode Based on Tissue Positioning

In various aspects, the reactions of the ultrasonic instrument may bebased on whether tissue is present within the end effector, the type oftissue located in the end effector, or the compressibility orcomposition of the tissue located in the end effector. Accordingly, thegenerator or the ultrasonic surgical instrument may contain and/orexecute instructions to perform algorithms to control the time betweenclamping the tissue in the jaws of the end effector and the activationof the ultrasonic transducer to treat the tissue. If tissue is notsensed, the ultrasonic generator activation buttons or pedals may beassigned different meanings to execute different functions. In oneaspect, an advanced energy device may employ the detection of thepresence of tissue within the jaws of the end effector as the queue foractivating the ultrasonic transducer, thereby starting the tissuecoagulation cycle. In another aspect, the compressive properties andsituational awareness may enable automatic activation of the device toalso adjust the parameters of the algorithm for the type of tissuesensed. For example, the advanced generator may ignore activations ofbuttons or foot pedals unless tissue is sensed in contact with the jawsof the end effector. This configuration would eliminate inadvertentactivation queues that would allow the device to be operated in asimpler manner.

Accordingly, an advanced generator, such as advanced generatorsdescribed in connection with FIGS. 1-42, and/or surgical instruments,such as ultrasonic surgical instruments described throughout thisdisclosure, may be configured to operate in a switchless mode. In aswitchless mode, the ultrasonic device is automatically activated incoagulation mode upon sensing or detecting the presence of tissue in thejaws of the end effector. In one aspect, when operating in automaticenergy activation (or “switchless” mode) mode, control algorithmcontrolling the activation of the ultrasonic surgical instrument can beconfigured to apply less energy initially to the ultrasonic instrumentthan if activated when not operating in the switchless mode. Further,the ultrasonic generator or instrument can be configured to determineboth contact with and the type of tissue located in the jaws of the endeffector. Based on sensing or detecting the presence of tissue in thejaws of the end effector, control algorithms executed either by aprocessor or control circuit of the generator or ultrasonic instrumentcould run the ultrasonic instrument in switchless mode and could adjustthe algorithm to achieve the best overall coagulation of the tissue inthe jaws of the end effector. In other aspects, in lieu of automaticallyactivating the surgical instrument and/or generator, control algorithmsexecuted by a processor or control circuit of the generator orultrasonic instrument could prevent activation of the generator orultrasonic instrument unless the presence of tissue is detected withinthe end effector.

In one aspect, the present disclosure provides an algorithm executed bya processor or control circuit located either in the generator orhandheld ultrasonic instrument to determine the presence of tissue andthe type of tissue located within the jaws of the end effector. In oneaspect, the control algorithm can be configured to determine that tissueis located within the end effector via techniques described herein fordetermining tissue location as described below under the headingDETERMINING TISSUE LOCATION VIA ELECTRODE CONTINUITY. For example, acontrol algorithm can be configured to determine whether tissue islocated within the end effector according to whether there is anycontinuity between electrodes (as described below) and, accordingly,activate the surgical instrument (e.g., by causing the generator towhich the surgical instrument is coupled to begin applying power to thesurgical instrument) automatically upon detecting tissue or permitactivation of the surgical instrument. When the surgical instrumentand/or generator is being operated in switchless mode, the controlalgorithm can further be configured to activate the surgical instrumentat a particular power level, which may or may not be different that astandard initial activation power level for the surgical instrument. Insome aspects, a control algorithm can be configured to activate orpermit activation of the surgical instrument according to the particulartype or composition of the tissue, which can be detected via, e.g.,techniques described below under the heading DETERMINING TISSUECOLLAGEN-TO-ELASTIN RATIO ACCORDING TO IR SURFACE REFLECTANCE ANDEMISSIVITY. For example, the control algorithm can be configured toactivate the surgical instrument when tissue having a high collagencomposition has been grasped, but not necessarily activate the surgicalinstrument when tissue having a high elastin composition has beengrasped. In some aspects, a control algorithm can be configured toactivate or permit activation of the surgical instrument according towhether the grasped tissue is located at a particular position withinthe end effector or whether a particular amount of tissue has beengrasped by the end effector via, e.g., techniques described below underthe heading DETERMINING TISSUE LOCATION VIA ELECTRODE CONTINUITY. Forexample, the control algorithm can be configured to activate thesurgical instrument when the grasped tissue covers a particularpercentage of the end effector. As another example, the controlalgorithm can be configured to activate the surgical instrument when thegrasped tissue is located at the distal end of the end effector.

In other aspects, a control algorithm can be configured to determinewhether tissue has been grasped by the end effector, the tissue type orcomposition, and other characteristics of the end effector or the tissuevia a situational awareness system, as described in U.S. ProvisionalPatent Application Ser. No. 62/659,900, titled METHOD OF HUBCOMMUNICATION, filed Apr. 19, 2018, which is hereby incorporated byreference in its entirety, and under the heading SITUATIONAL AWARENESS.In these aspects, a surgical hub 106 (FIGS. 1-11) to which the surgicalinstrument and/or generator is connected can receive data from thesurgical instrument, generator, and/or other medical devices utilized inthe operating theater and make inferences about the surgical procedure,or a particular step thereof, being performed. Accordingly, thesituational awareness system can infer whether and what type(s) oftissue are being operated on at any given instant or step and then acontrol algorithm can control the surgical instrument accordingly,including automatically activating the surgical instrument accordingly.For example, the control algorithm could be configured to automaticallyactivate or permit activation of the surgical instrument when the tissuegrasped by the end effector corresponds to the tissue type or tissuecomposition expected by the situational awareness system.

With the ability to detect whether or not the instrument is contactingtissue, and what type of tissue when in contact, the ultrasonicinstrument can be operated in a switchless mode of operation whereoperation is permitted based on the sensing ability of the ultrasonicinstrument. In some aspects, a control algorithm can be configured toignore actuations of activation buttons, foot pedals, and other inputdevices coupled to the generator and/or the ultrasonic surgicalinstrument unless tissue is sensed in contact with the jaws/end effectorof the surgical instrument, thereby preventing unintended activations ofthe instrument. In some aspects, a control algorithm can be configuredto assign different meanings to the inputs of activation buttons, footpedals, and other input devices coupled to the generator and/or theultrasonic surgical instrument according to whether tissue is sensed incontact with the jaws/end effector of the surgical instrument. Forexample, when tissue is present in the end effector, a control algorithmcan be configured to activate the surgical instrument in response to anactivation button being actuated; however, when tissue is not presentwithin the end effector, the control algorithm can be configured toexecute some different or secondary action when the activation button isactuated.

The ability to determine the lack of tissue present in the jaws of theend effector acts as a permissive to allow the instrument to change toswitchless mode and then initiate an automatic coagulation cycle ofoperation when tissue is then detected, leading to greater uptime use ofthe instrument and allowing the user to proceed based on its predictivecapability. The ability to further detect tissue type in addition todetecting the presence of tissue allows the algorithm to adjust andcalculate the best coagulation opportunity.

Tuning an Ultrasonic System According to Tissue Composition

In various aspects, an ultrasonic surgical instrument can include aprocessor or control circuit executing an adaptive ultrasonic bladecontrol algorithm for detecting the composition of the tissue grasped byor at the end effector and controlling operational parameters of theultrasonic transducer and/or ultrasonic blade accordingly. The tissuecomposition can include, for example, the ratio of collagen to elastinin the tissue, the stiffness of the tissue, or the thickness of thetissue. The operational parameters controlled or regulated by theadaptive ultrasonic blade control algorithm can include, for example,the amplitude of the ultrasonic blade, the temperature or heat flux ofthe ultrasonic blade, and so on. The adaptive ultrasonic blade controlalgorithm can be executed by a control circuit or processor locatedeither in the generator or the surgical instrument.

In one example described in further detail below, the adaptiveultrasonic blade control algorithm can be configured to control theamplitude of the ultrasonic blade according to the collagen-to-elastinratio of the tissue. The collagen-to-elastin ratio of the tissue can bedetermined via a variety of techniques, such as those described below.In another example described in further detail below, the adaptiveultrasonic blade control algorithm can be configured to control theultrasonic transducer/ultrasonic blade to provide a longer warming timeand a lower end temperature of the ultrasonic blade the lower thecollagen content of the tissue is.

Determining Tissue Collagen-to-Elastin Ratio According to FrequencyShift

In various aspects, a control algorithm can be configured to determinethe collagen-to-elastin ratio of a tissue (e.g., to tune the amplitudeof the distal tip of an ultrasonic blade) by detecting the naturalfrequency of an ultrasonic blade and the shifts in the ultrasonic bladewaveform. For example, the techniques described in connection with FIGS.1-54 may be employed to detect the ratio of collagen to elastin of thetissue located in an end effector of an ultrasonic instrument. In oneaspect, the present disclosure provides an adaptive ultrasonic bladecontrol algorithm to detect the natural frequency of the ultrasonicblade and shift in waveform to detect the composition of the tissue incontact with the ultrasonic blade. In another aspect, the adaptiveultrasonic blade control algorithm may be configured to detect thecollagen and elastin composition content of the tissue and adjust thetherapeutic heat flux of the ultrasonic blade based on the detectedcollagen content of the tissue. Techniques for monitoring the deviationof the natural frequency of the ultrasonic blade based on the tissuetype located in the jaws of the end effector of the ultrasonicinstrument are described herein in connection with FIGS. 1-54.Accordingly for conciseness and clarity of disclosure, such techniqueswill not be repeated here.

The ratio of elastin to collagen may be determined by monitoring theshift in the natural frequency of the ultrasonic blade and comparing thenatural frequency to a look-up table. The look-up table can be stored inmemory (e.g., memory 3326 of FIG. 31) and contains the ratio of elastinto collagen and a corresponding natural frequency shift for a particularratio as determined empirically.

Determining Tissue Collagen-to-Elastin Ratio According to IR SurfaceReflectance and Emissivity

In various aspects, a control algorithm can be configured to determinethe collagen-to-elastin ratio of a tissue (e.g., to tune the amplitudeof the distal tip of an ultrasonic blade) by determining the IRreflectivity of the tissue. For example, FIG. 59 illustrates anultrasonic system 130164 comprising an ultrasonic generator 130152coupled to an ultrasonic instrument 130150. The ultrasonic instrument130150 is coupled to an ultrasonic end effector 130400 via an ultrasonicwaveguide 130154. The ultrasonic generator 130152 may be integral withthe ultrasonic instrument 130150 or may be connected to the ultrasonicinstrument 130150 using wired or wireless electrical/electronic couplingtechniques. The end effector 130400 of the ultrasonic surgicalinstrument 130150 comprises IR sensors located on the clamp arm 130402(e.g., jaw member), in accordance with at least one aspect of thepresent disclosure. The ultrasonic generator 130152 and/or theultrasonic instrument 130150 may be coupled to the surgical hub 130160and/or the cloud 130162 over wireless or wired connections, as describedin connection with FIGS. 1-11.

FIG. 60 illustrates an IR reflectivity detection sensor circuit 130409that may be mounted or formed integrally with the clamp arm 130402 ofthe ultrasonic end effector 130400 to detect tissue composition, inaccordance with at least one aspect of the present disclosure. The IRsensor circuit 130409 includes an IR source 130416 (e.g., and IRtransmitter) and IR detector 130418 (e.g., an IR receiver). The IRsource 130416 is coupled to a voltage source V. A current is generatedthrough R2 when the control circuit 130420 closes the switch SW1. Whenthe switch SW1 is closed, the IR source 130416 emits IR energy towardsthe tissue 130410 (e.g., tissue clamped or situated between the clamparm 130402 and the ultrasonic blade 130404). Some of the emitted IRenergy is absorbed by the tissue 130410, some of the emitted IR energyis transmitted through the tissue 130410, and some of the emitted IRenergy is reflected by the tissue 130410. The IR detector 130418receives the IR energy reflected by tissue 130410 and generates anoutput voltage V₀ or signal, which is applied to the control circuit130420 for processing.

With reference to FIGS. 59 and 60, in one aspect, the ultrasonicgenerator 130152 includes the control circuit 130420 to drive the IRsource 130416 and IR detector 130418 located on or in the clamp arm130402 of the ultrasonic end effector 130400. In other aspects, theultrasonic instrument 130150 includes the control circuit 130420 todrive the IR source 130416 and IR detector 130418 located on or in theclamp arm 130402 of the ultrasonic end effector 130400. In eitheraspect, when tissue 130410 is grasped between the ultrasonic blade130404 and the clamp arm 130402, the IR source 130416 is energized bythe control circuit 130420 by closing switch SW1, for example, toilluminate the tissue with IR energy. In one aspect, the IR detector130418 generates a voltage V₀ that is proportional to the IR energyreflected by the tissue 130410. The total IR energy emitted by the IRsource 130416 equals the sum of the IR energy reflected by the tissue130410, the IR energy absorbed by the tissue 130410, and the IR energythat passes through the tissue 130410, plus any losses. Accordingly, thecontrol circuit 130420 or processor may be configured to detect thecollagen content of the tissue 130410 by the amount of IR energydetected by the IR detector 130418 relative to the total amount of IRenergy emitted by the IR source 130416. An algorithm takes into accountthe amount of energy absorbed by and/or transmitted through the tissue130410 to determine the collagen content of the tissue 130410. The IRsource 130416 and IR detector 130418 and algorithms are calibrated toprovide useful measurements of the collagen content of the tissue 130410using the principles of IR reflectivity.

The IR reflectivity detection sensor circuit 130409 shown in FIG. 60provides IR surface reflectance and emissivity to determine the ratio ofelastin to collagen. The IR reflectance may be employed to determinetissue composition for tuning the amplitude of an ultrasonic transducer.The refractive index is an optical constant that controls thelight-related reflection of IR light. The refractive index may beemployed to differentiate tissue types. For example, the refractiveindex contrast has been shown to differentiate between normal livertissue and hepatic metastases. The refractive index could be used as anabsolute or a comparative measure for tissue differentiation.

A comparative method employs an energy dissection device, such as anultrasonic blade 130404, for example, to determine the exact ratio (asdetailed above) and then to predict the collagen ratio for all furtheractuation using that index as a baseline. In this manner, an endoscopemay update the dissection device (e.g., ultrasonic blade 130404) basedon collagen ratio. The dissection device can fine-tune the forecastingeach time it is actuated to make an actual collagen denaturing firing.An alternative method may employ an absolute index with a look-up tablethat can differentiate between surface irregularities and sub-surfacecollagen concentration. Additional information about IR refractive indexproperties of tissue can be found in Visible To Near-Infrared RefractiveProperties Of Freshly-Excised Human-Liver Tissues: Marking HepaticMalignancies; Panagiotis Giannios, Konstantinos G. Toutouzas, MariaMatiatou, Konstantinos Stasinos, Manousos M. Konstadoulakis, George C.Zografos, and Konstantinos Moutzourisa; Sci. Rep. 2016; 6: 27910, whichis hereby incorporated by reference herein.

In other aspects, the ultrasonic dissection device can be configured tochange the ideal temperature of the ultrasonic blade control algorithmproportionately with the collagen ratio. For example, the ultrasonicblade temperature control algorithm can be modified based on thecollagen ratio received from the control circuit 130420. As one specificexample, the ultrasonic blade temperature control algorithm can beconfigured to lower the set of temperatures at which the ultrasonicblade 130404 is maintained and increase the hold time that theultrasonic blade 130404 is contacted with the tissue 130410 for higherconcentrations of collagen in the grasped tissue 130410. As anotherexample, the wait time for the algorithm to cycle through a fullactivation could be modified based on the collagen ratio. Varioustemperature control algorithms for ultrasonic blades are described inconnection with FIGS. 43-54.

FIG. 61 is a sectional view of an ultrasonic end effector 130400comprising a clamp arm 130402 and an ultrasonic blade 130404 accordingto one aspect of the present disclosure. The clamp arm 130402 comprisesIR reflectivity detection sensor circuits 130409 a, 130409 b that may bemounted or formed integrally with the clamp arm 130402 of the ultrasonicend effector 130400 to detect the composition of the tissue 130410. TheIR reflectivity detection sensor circuits 130409 a, 130409 b may bemounted on a flexible circuit substrate 130412, which is shown in plainview in FIG. 62. The flexible circuit substrate 130412 includes threeelongate elements 130408 a, 130408 b, 130408 c on which the IRreflectivity detection sensor circuits 130409 a, 130409 b and IR sensors130414 a, 130414 b are mounted. The IR sensors 130414 a, 130414 b mayinclude IR sources 130416 and IR detectors 130418 as shown in FIG. 60.

FIG. 63 is a logic flow diagram of a process 130200 depicting a controlprogram or a logic configuration to measure IR reflectance to determinetissue composition to tune the amplitude of the ultrasonic transducer.The process 130200 can be executed by a processor or control circuit ofa surgical instrument, such as the control circuit 760 of FIG. 18, or agenerator, such as the processor 902 of FIG. 21. For conciseness, theprocess 130200 will be described as being executed by a control circuit,but it should be understood that the following description encompassesthe aforementioned variations.

Accordingly, with reference to FIGS. 1-54 and FIGS. 59-63, in oneaspect, the control circuit energizes 130202 the IR source 130416 toapply IR energy to tissue 130410 clamped in an end effector 13400 of anultrasonic instrument 130150. The control circuit then detects 130204,via an IR detector 130418, the IR energy reflected by the tissue 130410.Accordingly, the control circuit determines 130206 the ratio of collagento elastin of the tissue 130410 based on the detected IR energyreflected by the tissue 130410. The control circuit adjusts 130208 theultrasonic blade temperature control algorithm, as discussed in U.S.Provisional Patent Application No. 62/692,768, titled SMART ENERGYDEVICES, based on the determined collagen-to-elastin ratio of thetissue. In one aspect, the collagen content of the tissue 130410 may bedetected by according to the reflectivity of an IR light source 130416.In another aspect, the lower the collagen content of the tissue 130410,the longer the warming time and the lower the end temperature of theultrasonic blade 130404. In yet another aspect, the tissue 130410composition may be tissue thickness or stiffness and could be used toaffect the ultrasonic blade transducer control program.

The ratio of elastin to collagen may be determined by monitoring the IRreflectance of the tissue and comparing the detected IR reflectance to alook-up table. The look-up table can be stored in memory (e.g., memory3326 of FIG. 31) and contains the ratio of elastin to collagen and acorresponding IR reflectance for a particular ratio as determinedempirically.

Determining Tissue Collagen-to-Elastin Ratio According to CollagenTransformation Point

Different types of tissues are composed of varying amounts of structuralproteins, such as collagen and elastin, which provide the differenttypes of tissue with different properties. As heat is applied to thetissue (e.g., by an ultrasonic blade), the structural proteins denature,which affects the tissue integrity and other tissue properties. However,the structural proteins denature at different known temperatures. Forexample, collagen denatures prior to elastin. Accordingly, by detectingat what temperature the properties of the tissue change, one can inferthe tissue composition (e.g., the ratio of collagen to elastin in thetissue). In various aspects, a control algorithm can be configured todetermine the collagen-to-elastin ratio of a tissue by determining thecollagen transformation point of the tissue. The control algorithm can,in turn, control various operational parameters of the surgicalinstrument, such as the amplitude of the ultrasonic blade, according tothe determined tissue composition. In one aspect, the control algorithmcan determine the collagen transformation point of the tissue bymeasuring the position of the clamp arm actuation member and the rate ofchange of its displacement while maintaining the load on the clamp armconstant. In another aspect, the control algorithm can determine thecollagen transformation point of the tissue by measuring the temperatureof the tissue/blade interface directly to identify the collagen/elastinpercentage.

FIGS. 16-19 illustrate schematically motorized clamp arm closuremechanisms. FIG. 40 is a system diagram 7400 of a segmented circuit 7401comprising a plurality of independently operated circuit segments 7402,7414, 7416, 7420, 7424, 7428, 7434, 7440, according to one aspect of thepresent disclosure, and FIG. 35 is a circuit diagram of variouscomponents of a surgical instrument with motor control functions,according to one aspect of the present disclosure. For example, FIG. 35illustrates a drive mechanism 7930, including a closure drivetrain 7934configured to close a jaw member to grasp tissue with the end effector.FIGS. 38-39 illustrate control systems 12950, 12970 for controlling therate of closure of the jaw member, such as a clamp arm portion of anultrasonic end effector, where FIG. 38 is a diagram of a control system12950 configured to provide progressive closure of a closure member asit advances distally to close the clamp arm to apply a closure forceload at a desired rate according to one aspect of this disclosure, andFIG. 39 illustrates a proportional-integral-derivative (PID) controllerfeedback control system 12970 according to one aspect of thisdisclosure. Accordingly, in the following description of an ultrasonicsystem comprising a motorized clamp arm controller to control theclosure rate and/or position of the clamp arm, reference should be madeto FIGS. 16-19 and 38-41.

In one aspect, a control algorithm can be configured to detect thecollagen transformation point of a grasped tissue and accordinglycontrol the delivery of ultrasonic energy to the tissue by controllingthe phase and/or amplitude of the ultrasonic transducer drive signal orrate of closure of the clamp arm. For example, in one aspect, a controlalgorithm can be configured to control the force applied to the tissueby the clamp arm according to the collagen transformation point. Thismay be achieved by measuring the position of the clamp arm actuationmember and its rate of change while maintaining the load of the clamparm constant within coaptation pressure within a set operational range(e.g., 130-180 psi) corresponding to the particular instrument type.

FIG. 64A is a graphical representation 130250 of the displacement of theclamp arm 1140 (FIG. 23) versus time as the clamp arm 1140 is closed toidentify the collagen transformation point, in accordance with at leastone aspect of the present disclosure. FIG. 64B is a magnified portion130256 of the graphical representation 130250 shown in FIG. 64A. Thehorizontal axis 130254 represents time (e.g., in sec.) and the verticalaxis 130252 represents clamp arm displacement δ (e.g., in mm). In oneaspect, a control algorithm can be configured to control the loadapplied to a tissue by the clamp arm 1140 (e.g., by controlling the rateof closure of the clamp arm 1140) as the ultrasonic blade 1128 (FIG. 23)heats the tissue according to the collagen transformation point of thetissue. In one such aspect, a control algorithm is configured to closethe clamp arm 1140 until the clamp arm load reaches a threshold, whichcan include a particular value (e.g., 4.5 lbs.) or a range of values(e.g., within a range of 3.5 to 5 lbs.). At that point, the controlalgorithm sets the clamp arm displacement rate of change threshold 6 andmonitors the displacement of the clamp arm 1140. As long as the rate ofchange of the clamp arm displacement remains within a predefinednegative limit (i.e., below the threshold θ), the control algorithm candetermine that the tissue is below the transformation temperature. Asshown in the graphical representation of FIGS. 64A and 64B, when thecontrol algorithm determines that the clamp arm displacement rate ofchange exceeds the threshold θ, the control algorithm can determine thatmelt temperature of the collagen has been reached.

In one aspect, once the control algorithm determines that the transitiontemperature has been reached, the control algorithm can be configured toalter the operation of the ultrasonic instrument accordingly. Forexample, the control algorithm can switch the surgical instrument fromload control (of the clamp arm 1140) to temperature control. In anotheraspect, the control algorithm can maintain the load control of the clamparm after the collagen transformation temperature has been reached andmonitor for when a clamp arm displacement rate of change threshold hasbeen reached. The second clamp arm displacement rate of change thresholdcan correspond to, for example, the transition temperature of elastin.The locations of the collagen and/or elastin transitions temperatures inthe plot 130258 of the clamp arm displacement over time can be referredto a “knee” in the plot 130258. Accordingly, in this aspect, the controlalgorithm can be configured to alter the operation of the ultrasonicinstrument according to whether the second clamp rate displacement rateof change threshold (or elastin “knee”) has been reached and alter theoperation of the ultrasonic instrument accordingly. For example, thecontrol algorithm can switch the surgical instrument from load control(of the clamp arm 1140) to temperature control when the elastin knee inthe plot 130258 is detected.

Collagen transformation should be constant for a given heat flux between45° and 50° C. for collagen, where elastin has a different melttemperature. Further, the temperature should flatten as the collagenabsorbs the heat. In some aspects, the control algorithm can beconfigured to sample the position of the clamp arm and/or clamp armdisplacement member at a higher rate around particular temperatures orwithin temperature ranges (e.g., the ranges for expected temperature forcollagen and/or elastin transformation) in order to precisely ascertainwhen the monitored events occur.

In the aspect depicted in FIGS. 64A and 64B, the control algorithm actsto change the surgical instrument from load control to temperaturecontrol when the collagen transformation point is detected at timet_(m). Without changing the surgical instrument to temperature control,the clamp arm displacement would increase geometrically, as shown in theprojected plot 130260. In one aspect, the control algorithm operating intemperature control mode lowers the amplitude of the ultrasonictransducer drive signal to change the heat flux generated by theultrasonic blade 1128, as shown by the flat portion of the plot 130258after the threshold 6 is reached. In some aspects, the control algorithmcan be configured to increase the amplitude of the ultrasonic transducerdrive signal after a particular period of time to, for example, measurethe rate of temperature increase to determine when the elastintransformation temperature has been reached. Accordingly, as the clamparm rate of closure approaches the next knee (i.e., the elastin knee)the clamp arm rate of closure can decrease. Load control of the clamparm 1140 can be beneficial because, in some cases, it can provide thebest sealing of vessels.

FIG. 65 is a logic flow diagram of a process 130300 depicting a controlprogram or a logic configuration to detect the collagen transformationpoint to control the rate of closure of the of the clamp arm or theamplitude of the ultrasonic transducer, in accordance with at least oneaspect of the present disclosure. The process 130300 can be executed bya control circuit or processor located in the surgical instrument or thegenerator. Accordingly, the control circuit executing the process 130300measures 130302 a position of the clamp arm actuation member and itsrate of change while maintaining the load on the clamp constant. Aspreviously described, in one aspect, the load on the clamp arm ismaintained within coaptation pressure within a suitable range (130-180psi) set by the ultrasonic surgical instrument. Once the jaws are takenup to a particular clamp arm load (e.g., 4.5 lbs.) or the clamp arm loadis within a particular range (e.g., 3.5-5 lbs.), the control circuitsets 130304 the clamp arm displacement rate of change and monitors theposition of the clamp arm actuation member for the period of time thatthe clamp arm displacement rate of change remains within a predefinednegative limit (corresponding to the tissue being below the collagentransformation temperature). Accordingly, the control determines 130306whether the clamp arm displacement rate of change exceeds the setthreshold or, in other words, determines whether the tissue has reachedthe transition temperature. If the transition temperature has beenreached, then the process 130300 proceeds along the YES branch and thecontrol circuit switches 130308 the surgical instrument to temperaturecontrol (e.g., controls the ultrasonic transducer to decrease ormaintain the temperature of the ultrasonic blade). In one aspect, thecontrol circuit continues monitoring for the collagen transformationtemperature. Alternatively, in the aspect depicted in FIG. 65, if thetransition temperature has not been reached, then the process 130300proceeds along the NO branch and the control circuit maintains 130310the load control of the clamp arm 1140 and monitors the clamp armdisplacement rate of change to determine when the next transition point(e.g., the elastin transition point) occurs for the grasped tissue. Thecontrol circuit can do this in order to, for example, prevent thetemperature of the tissue from increasing beyond the elastintransformation temperature.

It will be appreciated that the collagen transformation should beconstant for a given heat flux (45° C.-50° C.). It also will beappreciated that load control of the clamp arm 1140 can, in some cases,provide the best sealing for particular types of tissues (e.g.,vessels). During the period of time where collagen transformation isoccurring, the temperature of the tissue should flatten while thecollagen absorbs the heat. The control circuit can be configured tomodulate the rate at which data points are collected around a particulartemperature or temperatures of interests (e.g., transformationtemperatures). Further, the control circuit can tune the amplitude ofthe ultrasonic transducer drive signal to control the heat fluxgenerated by the ultrasonic blade 1128 at different points in thesurgical procedure. For example, the control circuit can decrease theultrasonic transducer amplitude during the period of collagentransformation. As another example, the control circuit can increase theultrasonic transducer amplitude to measure the rate at which thetemperature increases when the elastin knee occurs. It will beappreciated that as the elastin knee is approached, the rate oftemperature change will decrease.

In another aspect, a control algorithm can be configured to detect thecollagen transformation temperature to identify the collagen/elastinpercentage of the grasped tissue. As discussed above, the controlalgorithm can then control various operational parameters of thesurgical instrument according to the identified composition of thegrasped tissue.

FIG. 66 is a graphical representation 130350 of the identification ofthe collagen transformation temperature point to identify thecollagen/elastin ratio, in accordance with at least one aspect of thepresent disclosure. The vertical axis 130352 represents ultrasonictransducer impedance and the horizontal axis 130632 represents tissuetemperature. The point at which the rate of change of the ultrasonictransducer impedance shifts corresponds to the collagen/tissuecomposition of the tissue in an empirically determined manner. Forexample, if the rate of change of the ultrasonic transducer impedanceshifts at the first temperature 130362, then the tissue composition is100% collagen. Accordingly, if the rate of change of the ultrasonictransducer impedance shifts at the second temperature 130364, then thetissue composition is 100% elastin. If the rate of change of theultrasonic transducer impedance shifts between the first temperature130362 and the second temperature 130364, then the tissue composition isa mixture of collagen and elastin.

The collagen transformation temperature can be used to directly identifythe collagen/elastin percentage in the tissue and a control algorithmcan be configured to adjust the operation of the ultrasonic deviceaccordingly. As shown in FIG. 66, a plot 130356 represents the empiricalrelationship between ultrasonic transducer impedance and tissuetemperature. As indicated by the plot 130356, the impedance (Z) of theultrasonic transducer increases linearly at a first rate of change(slope) as a function of the temperature (T) at the tissue contact area.At the collagen transition temperature shown in the plot at the point130358, the rate of change of impedance (Z) as a function of temperature(T) decreases to a second rate of change. At the point 130358 where theslope of the plot 130356 changes, the collagen-to-elastin ratio cancorrespond to an empirically determined temperature 130360 (e.g., 85%).In one aspect, a control circuit or processor executing theaforementioned algorithm can be configured to determine at whattemperature the rate of ultrasonic transducer impedance changes and thenretrieve the corresponding tissue composition (e.g., percentage ofcollagen, percentage of elastin, or collagen/elastin ratio) from amemory (e.g., a look-up table).

FIG. 67 is a logic flow diagram of a process 130450 for identifying thecomposition of a tissue according to the change in ultrasonic transducerimpedance, in accordance with at least one aspect of the presentdisclosure. The process 130450 can be executed by a control circuit ofprocessor located in, for example, the surgical instrument or generator.Accordingly, the control circuit monitors 130452 the impedance (Z) ofthe ultrasonic transducer as a function of temperature (T). Aspreviously described, the temperature (T) at the interface of the tissueand ultrasonic blade may be inferred by the algorithms described herein.The control circuit determines 130454 the rate of change of theultrasonic transducer impedance ΔZ/ΔT. As the temperature at theultrasonic blade/tissue interface increases, the impedance (Z) increaseslinearly at a first rate, as shown in FIG. 66. Accordingly, the controlcircuit determines 130456 whether the slope ΔZ/ΔT has changed (e.g., hasdecreased). If the slope ΔZ/ΔT has not changed, then the process 130450proceeds along the NO branch and continues determining 130454 the slopeΔZ/ΔT. If the slope ΔZ/ΔT has changed, the control circuit determines130458 that the collagen transition temperature has been reached.

The ratio of elastin to collagen may be determined by monitoring thecollagen transformation point of the tissue and comparing the detectedcollagen transformation point to a look-up table. The look-up table canbe stored in memory (e.g., memory 3326 of FIG. 31) and contains theratio of elastin to collagen and a corresponding collagen transformationpoint for a particular ratio as determined empirically.

Adjusting Clamp Arm Force According to Tissue Location

In various aspects, a control algorithm can be configured to determinethe location of a tissue within or relative to an end effector andadjust the clamp arm force accordingly. In one aspect, tissue can beidentified or parameterized by measuring the compression force load onthe clamp arm and the position of the tissue within the jaw, e.g., wherethe tissue is located along the length of the ultrasonic blade. In oneaspect, the time to initial measured load on the clamp arm is measuredand then the compression rate on the tissue is measured to determinecompressibility of the tissue versus the amount of tissue located acrossthe length of the jaw. The rate of change of position of the clamp armactuator is monitored while in load control as a way to determine tissuecompressibility and therefore tissue type/disease state.

FIG. 68 is a graphical representation 130500 of the distribution ofcompression load across an ultrasonic blade 130404, in accordance withat least one aspect off the present disclosure. The vertical axis 130502represents the force applied to the tissue by the clamp arm 1140 and thehorizontal axis 130504 represents position. The ultrasonic blade 130404is dimensioned such that there are periodic nodes and antinodes thatoccur along the length of the blade. The location of the nodes/antinodesis determined by the wavelength of the ultrasonic displacement inducedin the ultrasonic blade 130404 by the ultrasonic transducer. Theultrasonic transducer is driven by an electrical signal of suitableamplitude and frequency. As is known in the art, a node is a point ofminimal or zero displacement of the ultrasonic blade 130404 and anantinode is a point of maximum displacement of the ultrasonic blade130404.

In the graphical representation 130500, the ultrasonic blade 130404 isrepresented such that the nodes and antinodes are aligned with theircorresponding position along the horizontal axis 130504. The graphicalrepresentation 130500 includes a first plot 130506 and a second plot130508. As represented by either of the plots 130506, 130508, thecompression force applied to the ultrasonic blade 130404 dropsexponentially from a proximal end of the ultrasonic blade 130404 to adistal end of the ultrasonic blade 130404. Thus, tissue 130410 locatedat the distal end of the ultrasonic blade 130404 is subjected to muchlower compression force as compared to tissue 130410 located closer tothe proximal end of the ultrasonic blade 130404. The first plot 130506can represent a default closure of the clamp arm 1140 where theresulting force applied to the distal tissue 130410 is F₁. Generally,the amount of force applied by the clamp arm 1140 to tissue 130410cannot be broadly increased without consideration because then too muchforce could be applied to tissue 130410 located proximally along theultrasonic blade 130404. However, by monitoring the location of thetissue 130410 along the ultrasonic blade 130404 (e.g., as discussedabove under the heading DETERMINING TISSUE LOCATION VIA IMPEDANCE CHANGEand below under the heading DETERMINING TISSUE LOCATION VIA ELECTRODECONTINUITY), a control algorithm can amplify the force applied to thetissue 130410 by the clamp arm 1140 in situations where tissue 130410 islocated only at the distal end of the ultrasonic blade 130404, as withthe situation shown in FIG. 68. For example, the second plot 130508 canrepresent a modified closure of the clamp arm 1140 where the controlalgorithm determines that tissue 130410 is located only at the distalend of the ultrasonic blade 130404 and correspondingly increases theforce applied to the distal tissue 130410 by the clamp arm 1140 to F₂(F₂>F₁).

FIG. 69 is a graphical representation 130520 of pressure applied totissue versus time, according to one aspect of the present disclosure.The vertical axis 130522 represents the pressure (e.g., in N/mm²)applied to the tissue and the horizontal axis 130524 represents time.The first plot 130526 represents a normal or default compression forceapplied to the distal tissue 130410 without amplification. During adefault closure of the clamp arm 1140, the compression force applied tothe tissue 130410 is maintained at a constant value after an initialramp-up period. The second plot 130528 represents the amplifiedcompression force applied to the distal tissue 130410 to compensate forthe presence of only distal tissue 130410. In the modified closure ofthe clamp arm 1140, the pressure is increased 130530 as compared to thedefault closure until eventually the amplified compression force isreturned 130532 to normal compression levels to prevent burning/meltingthrough the clamp arm 1140 pad.

Determining Tissue Location via Electrode Continuity

In various aspects, a control algorithm can be configured to determinethe location of a tissue within or relative to an end effector accordingto electrical continuity across an array of bipolar (i.e., positive andnegative) electrodes positioned along a jaw or jaws of the end effector.The location of the tissue detectable by the bipolar electrode array cancorrespond to the specific position of the tissue relative to the jaw(s)and/or the percentage of the jaw(s) covered by tissue. In one aspect,the positive and negative electrodes are separated by a physical gapsuch that electrical continuity is established between the electrodeswhen tissue bridges the positive and negative electrodes. The positiveand negative electrodes are configured in a matrix or array such that aprocessor or control circuit can be configured to detect where tissue islocated between the positive and negative electrodes by monitoring orscanning the electrode array. In one aspect, the bipolar electrode arraycan be positioned along one jaw of an end effector. Accordingly, acontrol circuit or processor coupled to the bipolar electrode array canbe configured to detect electrical continuity between adjacentelectrodes to detect the presence of tissue thereagainst. In anotheraspect, the bipolar electrode array can be positioned along opposingjaws of an end effector. Accordingly, a control circuit or processorcoupled to the bipolar electrode array can be configured to detectelectrical continuity between the opposing jaws to detect the presenceof tissue therebetween.

Determining what surface area of the jaw(s) is covered with tissueallows a control algorithm to determine the appropriate coaptationpressure for the amount of tissue grasped by the end effector and thencalculate the corresponding clamp arm load. The clamp arm load can beexpressed in terms of applied pressure (e.g., 130-180 psi) or appliedforce (e.g., 3.5-5 lbs. or nominally 4.5 lbs.). In some aspects, thebipolar electrode array can be delivered power from a monopolar orbipolar RF electrosurgical generator to the positive and negativeelectrodes. The generator power output may be a variety of constant,variable, or minimum values (e.g., 45 W, 35 W, or 5 W), a function ofvarious variables associated with the surgical instrument and/or thegenerator (e.g., amplitude of the ultrasonic blade or clamp arm force),or dictated by an algorithm for controlling the generator according toits power curve (e.g., during ramp up of the generator).

FIG. 70 illustrates an end effector 130400, including a single-jawelectrode array for detecting tissue location, in accordance with atleast one aspect of the present disclosure. In the depicted aspect, theend effector 130400 includes a first jaw 130430 having an electrodearray 130431 disposed thereon and a second jaw 130432. The electrodearray 130431 includes electrodes 130429 coupled to an energy source,such as an RF generator. The end effector 130400 can include an endeffector for an ultrasonic surgical instrument where the second jaw130432 is, for example, an ultrasonic blade 1128 (FIG. 23), anelectrosurgical instrument, an end effector for a surgical stapling andcutting instrument, and so on. The second jaw 130432 can include, forexample, an ultrasonic blade 1128 (FIG. 23) or a cooperating jaw of anelectrosurgical or surgical stapling and cutting instrument. In thedepicted aspect, the electrode array 130431 includes 12 electrodes130429 arranged in a generally herringbone-shaped pattern; however, thenumber, shape, and arrangement of the electrodes 130429 in the electrodearray 130431 are merely for illustrative purposes. Accordingly, theelectrode array 130431 can include various numbers, shapes, and/orarrangements of electrodes 130429. For example, the number of electrodes130429 can be adjusted according to the desired resolution for detectingtissue position.

In one aspect, the electrode array 130431 can include electrodes 130429that are separated by a physical gap and alternate in polarity or arecoupled to opposing terminals (i.e., a supply terminal and a returnterminal) of an energy source. For example, in the depicted aspect, theevenly numbered electrodes 130429 can be a first polarity (e.g.,positive polarity or coupled to a supply terminal of a power source) andthe odd numbered electrodes 130429 can be a second polarity (e.g.,negative or coupled to a return terminal of a power source).Accordingly, when tissue 130410 contacts adjacent electrodes 130429, thetissue 130410 physically and electrically bridges the bipolar electrodes130429 and allows current to flow therebetween. The flow of currentbetween bipolar electrodes 130429 can be detected by a control algorithmexecuted by a control circuit or processor coupled to the electrodearray 130431, thereby allowing the control circuit or processor todetect the presence of tissue 130410.

The detection of tissue by the electrode array 130431 can be representedgraphically by an activation matrix. For example, FIG. 71 illustrates anactivation matrix 130550 indicating the position of the tissue 130410according to the electrode array 130431 depicted in FIG. 70. Thevertical axis 130554 and the horizontal axis 130555 both represent theelectrodes 130429 of the electrode array 130431, where the numbers alongthe axes 130554, 130555 represent the correspondingly numberedelectrodes 130429. The activation regions 130552 indicate wherecontinuity is present between the corresponding electrodes 130429, i.e.,where tissue 130410 is present. In FIG. 70, a tissue 130410 is presentacross the first, second, and third electrodes 130429 and, as discussedabove, the electrodes 130429 can alternate in polarity in some aspects.Accordingly, there is electrical continuity between the first and secondelectrodes 130429 and the second and third electrodes 130429. It shouldbe noted that, in this described aspect, there would be no continuitybetween the first and third electrodes 130429 because they would be thesame polarity. The continuity between these electrodes 130429 isindicated graphically by the activation regions 130552 in the activationmatrix 130550. It should also be noted that the region 130553 bounded bythe activation regions 130552 is not indicated as activated because, inthis described aspect, an electrode 130429 cannot have continuity withitself. A control algorithm executed by a control circuit or processorcoupled to the electrode array 130431 can be configured to infer theposition of the tissue 130410 within the end effector 130400 (as thelocations of the electrodes 130429 would be known), the proportion ofjaws 130430, 130432 of the end effector 130400 covered by tissue 130410,and so on because the tissue location corresponds to the particularelectrodes 130429 where electrical continuity has been established.

FIG. 72 illustrates an end effector 130400 including a dual-jawelectrode array for detecting tissue location, in accordance with atleast one aspect of the present disclosure. In the depicted aspect, theend effector 130400 includes a first jaw 130430 having a first electrodearray 130431 disposed thereon and a second jaw 130432 having a secondelectrode array 130433 disposed thereon. The electrode arrays 130431,130433 each include electrodes 130429 coupled to an energy source, suchas an RF generator. The end effector 130400 can include an end effectorfor an electrosurgical instrument, an end effector for a surgicalstapling and cutting instrument, and so on. As discussed above, thenumber, shape, and/or arrangement of electrodes 130429 can be varied invarious aspects. For example, in FIG. 75 the electrode arrays 130431,130433 are arranged in overlapping tiled or rectangular patterns.

In one aspect, the opposing electrodes 130429 of the electrode arrays130431, 130433 are separated by a physical gap, and each electrode array130431, 130433 is of an opposing polarity or is coupled to an opposingterminal (i.e., a supply terminal and a return terminal) of an energysource. For example, in the depicted aspect, the first electrode array130431 can be a first polarity (e.g., positive polarity or coupled to asupply terminal of a power source) and the second electrode array 130433can be a second polarity (e.g., negative or coupled to a return terminalof a power source). Accordingly, when tissue 130410 contacts anelectrode 130429 of each of the opposing electrode arrays 130431,130433, the tissue 130410 physically and electrically bridges thebipolar electrodes 130429 and allows current to flow therebetween. Theflow of current between bipolar electrodes 130429 can be detected by acontrol algorithm executed by a control circuit or processor coupled tothe electrode arrays 130431, 130433, thereby allowing the controlcircuit or processor to detect the presence of tissue 130410.

As discussed above, an activation matrix can graphically represent thepresence of tissue. For example, FIG. 73 illustrates an activationmatrix 130556 indicating the position of the tissue 130410 as depictedin FIG. 74. The vertical axis 130557 represents the electrodes 130429 ofthe first electrode array 130431 and the horizontal axis 130558represents the electrodes 130429 of the second electrode array 130433,where the numbers along the axes 130557, 130558 represent thecorrespondingly numbered electrodes 130429 for each electrode array130431, 130433. The activation regions 130552 indicate where continuityis present between the corresponding electrodes 130429, i.e., wheretissue 130410 is present. In FIG. 74, a tissue 130410 is positionedagainst the first, second, and third electrodes 130431 a, 130431 b,130431 c of the first electrode array 130431 and the first, second, andthird electrodes 130433 a, 130433 b, 130433 c of the second electrodearray 130433. Accordingly, there is electrical continuity between eachof these sets of electrodes of the opposing electrode arrays 130431,130433 as current can flow between these opposing sets of electrodes.The electrodes between which there is continuity due to the position ofthe grasped tissue 130410 are indicated graphically by the activationregions 130552 in the activation matrix 130556 of FIG. 73. Further,because the tissue 130410 is not positioned against the fourth, fifth,and sixth electrodes 130431 d, 130431 e, 130431 f of the first electrodearray 130431 and the fourth, fifth, and sixth electrodes 130433 d,130433 e, 130433 f of the second electrode array 130433, there is noelectrical continuity between these electrodes. A control algorithmexecuted by a control circuit or processor coupled to the electrodearrays 130431, 130433 can be configured to infer the position of thetissue 130410 within the end effector 130400 (as the locations of theelectrodes 130429 would be known, as indicated in FIG. 74), theproportion of jaws 130430, 130432 of the end effector 130400 covered bytissue 130410, and so on because the tissue location corresponds to theparticular electrodes 130429 where electrical continuity has beenestablished. In the depicted example, the activated electrodes of thefirst and second electrode arrays 130431, 130433 are the electrodes130429 that overlap and where there is tissue 130410 situatedtherebetween.

In another aspect, the end effector can be configured to transmit aplurality of signals or pings at varying frequencies and the electrodearray can be coupled to a circuit, including corresponding band-passfilters that can each detect a particular frequency signal or signalsthrough a frequency transform. Various portions of the electrode arraycircuit can include band-pass filters tuned to different frequencies.Therefore, the location of the tissue grasped by the end effectorcorresponds to the particular detected signals. The signals can betransmitted, for example, at a nontherapeutic frequency (e.g., atfrequencies above the therapeutic frequency range for RF electrosurgicalinstruments). The electrode array circuit can include, for example, aflex circuit.

FIG. 75 illustrates an end effector 130400 including a first jaw 130430having a first segmented electrode array 130431 and a second jaw 130432having a second segmented electrode array 130433, according to at leastone aspect of the present disclosure. Further, FIG. 76 illustrates atissue 130410 that is grasped by the end effector 130400 overlaying thesecond jaw 130432. In one aspect, the first electrode array 130431 isconfigured to transmit signals at various frequencies (e.g.,nontherapeutic frequencies) and the second electrode array 130433 isconfigured to receive the signals through a tissue 130410 grasped by theend effector 130400 (i.e., when a tissue 130410 is contacting bothelectrode arrays 130431, 130433). The second electrode array 130433 caninclude a segmented electrode array circuit 130600, as shown in FIG. 77,wherein each circuit segment includes a band-pass filter 130601 coupledto each electrode 130602 of the second electrode array 130433. Eachband-pass filter 130601 can include one or more capacitors 130604 andone or more inductors 130606, wherein the number, arrangement, andvalues of the capacitors 130604 and inductors 130606 can be selected totune each band-pass filter 130601 to a particular frequency or frequencyband. As the tissue 130410 functions as the signal-conducting mediumbetween the electrode arrays 130431, 130433 and different portions ofthe second electrode array 130433 are tuned to detect signals of varyingfrequencies (via differently tuned band-pass filters 130601), a controlalgorithm executed by a control circuit or processor coupled to theelectrode arrays 130431, 130433 can be configured to infer the positionof the tissue 130410 according to which signals are detected thereby. Inthe depicted aspect, the electrode arrays 130431, 130433 include sixelectrode segments 130602 arranged in a generally tiled pattern with asemicircular end segment; however, the number, shape, and arrangement ofthe electrodes 130602 in the electrode arrays 130431, 130433 are merelyfor illustrative purposes. Accordingly, the electrode arrays 130431,130433 can include various numbers, shapes, and/or arrangements ofelectrodes 130602. For example, the number of electrodes 130602 can beadjusted according to the desired resolution for detecting tissueposition.

FIG. 78 is a graphical representation 130650 of the frequency responsecorresponding to the tissue 130410 grasped in FIG. 76, in accordancewith at least one aspect of the present disclosure. The vertical axis130652 represents amplitude and the horizontal axis 130654 represents RFfrequency. In one aspect, the second electrode array 130433 includes afirst electrode circuit segment 130602 a tuned to a frequency banddefined by a first center frequency f_(s1) (e.g., 5 MHz), a secondelectrode circuit segment 130602 b tuned to a frequency band defined bya second center frequency f_(s2) (e.g., 10 MHz), a third electrodecircuit segment 130602 c tuned to a frequency band defined by a thirdcenter frequency f_(s3) (e.g., 15 MHz), and a fourth electrode circuitsegment 130602 d tuned to a frequency band defined by a fourth centerfrequency f_(s4) (e.g., 20 MHz). As depicted in FIG. 78, the sensingfrequency bands define a sensing frequency range 130658 above thetherapeutic frequency range 130656 defined by f_(T1) (e.g., 300 kHz) tof_(T2) (e.g., 500 kHz) and/or a preferred therapeutic frequency (e.g.,350 kHz). In one aspect, the center sensing frequencies f_(s1), f_(s2),f_(s3), f_(s4) in the sensing frequency range 130658 are each separatedby a defined frequency value (e.g., 5 MHz). Further, although thesensing frequency range 130658 is illustrated as including four sensingfrequency bands, this is merely for illustrative purposes. In thedepicted example, the grasped tissue 130410 is contacting the second,third, and fourth electrode circuit segments 130602 b, 130602 c, 130602d. Accordingly, the detected frequency response includes peaks 130655 b,130655 c, 130655 d at each of the corresponding frequencies. A controlalgorithm could therefore infer the position of the tissue 130410 fromthe detected frequency response, i.e., the control circuit can determinethat the tissue 130410 is positioned within the end effector 130400 suchthat it is contacting the second, third, and fourth electrode circuitsegments 130602 b, 130602 c, 130602 d and not other circuit segments.The control algorithm can thus infer the position of the tissue 130410relative to the jaws 130430, 130432 of the end effector 130400 and/orthe percentage of the jaws 130430, 130432 in contact with the tissue130410.

Adaptive Ultrasonic Blade Temperature Monitoring

In one aspect, an adaptive ultrasonic blade control algorithm may beemployed to adjust various operational parameters of the ultrasonicsystem based on the temperature of the ultrasonic blade. The operationalparameters controlled or regulated by the adaptive ultrasonic bladecontrol algorithm can include, for example, the amplitude of theultrasonic blade, the control signal driving the ultrasonic transducer,the pressure applied by the clamp arm, and so on. The adaptiveultrasonic blade control algorithm can be executed by a control circuitor processor located either in the generator or the surgical instrument.

In one example described in further detail below, the adaptiveultrasonic blade control algorithm dynamically monitors the temperatureof the ultrasonic blade and adjusts the amplitude of the ultrasonicblade and/or the signal provided to the ultrasonic transduceraccordingly. In another example described in further detail below, theadaptive ultrasonic blade control algorithm dynamically monitors thetemperature of the ultrasonic blade and adjusts the clamp arm pressureaccordingly. The adaptive ultrasonic blade control algorithm can measurethe temperature of the ultrasonic blade via various techniques, such asby analyzing the frequency spectrum of the ultrasonic transducer asdiscussed above under the heading TEMPERATURE INFERENCE. Othertechniques for determining the temperature of the ultrasonic bladeemploy non-contact imaging. These and other techniques are described indetail herein and additional detail may be found in U.S. ProvisionalPatent Application No. 62/692,768, titled SMART ENERGY DEVICES.

Adjusting Ultrasonic System Parameters According to Temperature

In one aspect, the adaptive ultrasonic blade control algorithm can beconfigured to adjust operational parameters of the ultrasonic systembased on the temperature of the ultrasonic blade. As discussed aboveunder the heading TEMPERATURE INFERENCE, the natural frequency of theultrasonic blade/transducer moves with temperature, and thus, thetemperature of the ultrasonic blade can be inferred from the phase anglebetween the voltage and current signals applied to drive the ultrasonictransducer. Further, the ultrasonic blade temperature corresponds to thetissue temperature. In some aspects, the adaptive ultrasonic bladecontrol algorithm can be configured to detect the ultrasonic bladetemperature and modulate the surgical instrument's operationalparameters according to the temperature. The operational parameters caninclude, for example, the frequency of the ultrasonic transducer drivesignal, the amplitude of the ultrasonic blade (which can, for example,correspond to the magnitude or amplitude of the electrical currentsupplied to the ultrasonic transducer), the pressure applied by theclamp arm, and so on. The adaptive ultrasonic blade control algorithmcan be executed by a control circuit or processor located either in thegenerator or the surgical instrument.

Accordingly, in one aspect, the adaptive ultrasonic blade controlalgorithm detects the resonant frequency of the ultrasonic blade, asdescribed previously under the heading TEMPERATURE INFERENCE, and thenmonitors the resonant frequency over time in order to detect a modalshift in the resonant frequency waveform. A shift in the resonantwaveform can be correlated to the occurrence of a system change, such asan increase in the temperature of the ultrasonic blade. In some aspects,an adaptive ultrasonic blade control algorithm can be configured toadjust the amplitude of the ultrasonic drive signal, and therefore theamplitude of the ultrasonic blade displacement, in order to measure thetemperature of the tissue. In other aspects, an adaptive ultrasonicblade control algorithm can be configured to control the amplitude ofthe ultrasonic drive signal, and therefore the amplitude of theultrasonic blade displacement, according to the temperature of theultrasonic blade and/or tissue in order to hold the temperature of theultrasonic blade and/or tissue to a predefined temperature or withinpredefined thresholds (e.g., to allow the ultrasonic blade to cool ifits temperature is becoming too high). In still other aspects, anadaptive ultrasonic blade control algorithm can be configured tomodulate the RF power and waveform of an electrosurgical instrument inorder to, for example, minimize temperature overshoot or change theultrasonic blade heat flux, according to the tissue impedance, tissuetemperature, and/or ultrasonic blade temperature. Further detailsregarding these and other functions have been described in reference toFIGS. 95-100, for example.

FIG. 79 is a graphical representation 130700 of the frequency of theultrasonic transducer system as a function of drive frequency andultrasonic blade temperature drift, in accordance with at least oneaspect of the present disclosure. The horizontal axis 130704 representsthe drive frequency (e.g., in Hz) applied to the ultrasonic system(e.g., the ultrasonic transducer and/or ultrasonic blade) and thevertical axis 130702 represents the resulting impedance phase angle(e.g., in rads). The first plot 130706 represents a characteristicresonant waveform of the ultrasonic system at normal or ambienttemperature. As can be seen in the first plot 130706, the ultrasonicsystem is in phase when driven at the excitation frequency f_(e)(because the impedance phase angle is at or near 0 rads). Accordingly,f_(e) represents the resonant frequency of the ultrasonic system atambient temperature. The second plot 130708 represents a characteristicwaveform of the ultrasonic system when the temperature of the ultrasonicsystem has been elevated. As indicated in FIG. 79, as the temperature ofthe ultrasonic system increases, the characteristic waveform (depictedby the first plot 130706) of the ultrasonic blade and ultrasonictransducer shifts to the left, e.g., to a lower frequency range. Due tothe shift in the ultrasonic system frequency waveform, the ultrasonicsystem is no longer in phase when driven at the excitation frequencyf_(e). Rather, the resonant frequency has shifted lower to f′_(e).Therefore, a control circuit coupled to the ultrasonic system can detector infer the temperature change in the ultrasonic system by detectingthe change in the resonant frequency of the ultrasonic system and/ordetecting when the ultrasonic system is out of phase when driven at apreviously established resonant frequency.

Correspondingly, in some aspects, a control circuit coupled to theultrasonic system can be configured to control the drive signal appliedto the ultrasonic system by the generator according to the inferredtemperature of the ultrasonic system in order to maintain the ultrasonicsystem in phase. Maintaining the ultrasonic system in phase can beutilized to, for example, control the temperature of the ultrasonicsystem. As discussed above, the resonant frequency at which the voltageand current signals are in phase shifts from f_(e) (e.g., 55.5 kHz) atnormal temperature to f′_(e) as the temperature of the ultrasonic bladeand/or ultrasonic transducer increases. Therefore, as the temperature ofthe ultrasonic system increases, a control circuit can control thegenerator to shift the frequency at which the ultrasonic system isdriven from f_(e) to f′_(e) to maintain the ultrasonic system in phasewith the generator drive signal. For additional description of adaptiveultrasonic blade control algorithms, please refer to the descriptionassociated with FIGS. 43A-54 hereinabove.

FIG. 80 is a graphical representation 130750 of temperature of theultrasonic transducer as a function of time, in accordance with at leastone aspect of the present disclosure. The vertical axis 130752represents the temperature of the ultrasonic transducer, and thehorizontal axis 130754 represents time. In one aspect, as the ultrasonictransducer temperature (represented by the plot 130756) meets or exceedsa temperature threshold T₁, the adaptive ultrasonic blade controlalgorithm controls the ultrasonic transducer to maintain the temperatureof the ultrasonic transducer at or below the threshold temperature T₁.The adaptive ultrasonic blade control algorithm can control thetemperature of the ultrasonic transducer by, for example, modulating thepower and/or drive signal applied to the ultrasonic transducer.Additional description of algorithms and techniques for controlling thetemperature of an ultrasonic blade/transducer can be found under theheadings FEEDBACK CONTROL and ULTRASONIC SEALING ALGORITHM WITHTEMPERATURE CONTROL and in U.S. Provisional Patent Application No.62/640,417, titled TEMPERATURE CONTROL IN ULTRASONIC DEVICE AND CONTROLSYSTEM THEREFOR, filed Mar. 8, 2018, the disclosure of which is herebyincorporated by reference herein.

FIG. 81 is a graphical representation of the modal shift of resonantfrequency based on the temperature of the ultrasonic blade moving theresonant frequency as a function of the temperature of the ultrasonicblade, in accordance with at least one aspect of the present disclosure.In the first graph 130800, the vertical axis 130802 represents thechange in resonant frequency (Δf), and the horizontal axis 130804represents the ultrasonic transducer drive frequency of the generator.In the second, third, and fourth graphs 130810, 130820, 130830, thevertical axes 130812, 130822, 130832 represents frequency (f), current(I), and temperature (T), respectively, and the horizontal axes 130814,130824, 130834 represent time (t). The first graph 130810 representsfrequency shift of the ultrasonic system due to temperature change. Thesecond graph 130820 represents current in the ultrasonic transducer, oramplitude adjustment, in order to hold stable frequency and temperature.The third graph 130830 represents temperature change of the tissueand/or ultrasonic system. The set of graphs 130800, 130810, 130820,130830 in conjunction demonstrate the functioning of a control algorithmconfigured to control the temperature of an ultrasonic system.

The control algorithm can be configured to control the ultrasonic system(e.g., ultrasonic transducer and/or ultrasonic blade) when thetemperature of the ultrasonic system approaches a temperature thresholdT₁. In one aspect, the control algorithm can be configured to determinethat the temperature threshold T₁ is being approached or has beenreached according to whether the resonant frequency of the ultrasonicsystem has dropped by a threshold Δf_(R). As indicated by the firstgraph 130800, the change in frequency threshold Δf_(R) corresponding tothe threshold temperature T₁ can, in turn, be a function of the drivefrequency f_(D) of the ultrasonic system (as represented by the plot130806). As indicated by the second graph 130810 and the fourth graph130830, as the temperature of the tissue and/or ultrasonic bladeincreases (represented by the temperature plot 130836), the resonantfrequency correspondingly decreases (represented by the frequency plot130816). As the temperature plot 130836 approaches a temperaturethreshold T₁ (e.g., 130° C.) at time t₁, the resonant frequency hasdropped from f₁ to f₂, causing the resonant frequency to reach thecontrol algorithm's change in frequency threshold Δf_(R) and therebycausing the control algorithm act to stabilize the ultrasonic systemtemperature. By monitoring the change in resonant frequency of theultrasonic system, the adaptive ultrasonic blade control algorithm canthus monitor the temperature of the ultrasonic system. Further, theadaptive ultrasonic blade control algorithm can be configured to adjust(e.g., decrease) the electrical current applied to the ultrasonictransducer or otherwise adjust the amplitude of the ultrasonic blade(represented by the current plot 130826) in order to stabilize thetissue and/or ultrasonic blade temperature and/or the resonant frequencywhen the temperature meets or exceeds the threshold T₁.

In another aspect, the adaptive ultrasonic blade control algorithm canbe configured to adjust (e.g., decrease) the pressure applied by theclamp arm to the tissue when the temperature meets or exceeds thethreshold T₁. In various other aspects, the adaptive ultrasonic bladecontrol algorithm can be configured to adjust a variety of otheroperational parameters associated with the ultrasonic system accordingto the temperature. In another aspect, the adaptive ultrasonic bladecontrol algorithm can be configured to monitor multiple temperaturethresholds. For example, a second temperature threshold T₂ canrepresent, for example, a melt or failure temperature of the clamp arm.Accordingly, the adaptive ultrasonic blade control algorithm can beconfigured to take the same or different actions according to theparticular temperature threshold that has been met or exceeded.

In various aspects, non-contact imaging may be employed to determine thetemperature of the ultrasonic blade in addition to or in lieu of theaforementioned techniques. For example, short-wave thermography may beemployed to measure blade temperature by imaging the blade from thestationary surrounding ground via a CMOS imaging sensor. Thermographicnon-contact monitoring of the ultrasonic waveguide or ultrasonic bladetemperature may be employed to control tissue temperature. In otheraspects, non-contact imaging may be employed to determine surfaceconditions and finish of the ultrasonic blade to improve the temperatureof tissue and /or ultrasonic blade through near IR detection techniques.

Determining Jaw State

A challenge with ultrasonic energy delivery is that ultrasonic acousticsapplied on the wrong materials or the wrong tissue can result in devicefailure, for example, clamp arm pad burn through or ultrasonic bladebreakage. It is also desirable to detect what is located in the jaws ofan end effector of an ultrasonic device and the state of the jawswithout adding additional sensors in the jaws. Locating sensors in thejaws of an ultrasonic end effector poses reliability, cost, andcomplexity challenges.

Ultrasonic spectroscopy smart blade algorithm techniques may be employedfor estimating the state of the jaw (clamp arm pad burn through,staples, broken blade, bone in jaw, tissue in jaw, back-cutting with jawclosed, etc.) based on the impedance

${Z_{g}(t)} = \frac{V_{g}(t)}{I_{g}(t)}$

of an ultrasonic transducer configured to drive an ultrasonic transducerblade, in accordance with at least one aspect of the present disclosure.The impedance Z_(g)(t), magnitude |Z|, and phase cp are plotted as afunction of frequency f.

Dynamic mechanical analysis (DMA), also known as dynamic mechanicalspectroscopy or simply mechanical spectroscopy, is a technique used tostudy and characterize materials. A sinusoidal stress is applied to amaterial, and the strain in the material is measured, allowing thedetermination of the complex modulus of the material. The spectroscopyas applied to ultrasonic devices includes exciting the tip of theultrasonic blade with a sweep of frequencies (compound signals ortraditional frequency sweeps) and measuring the resulting compleximpedance at each frequency. The complex impedance measurements of theultrasonic transducer across a range of frequencies are used in aclassifier or model to infer the characteristics of the ultrasonic endeffector. In one aspect, the present disclosure provides a technique fordetermining the state of an ultrasonic end effector (clamp arm, jaw) todrive automation in the ultrasonic device (such as disabling power toprotect the device, executing adaptive algorithms, retrievinginformation, identifying tissue, etc.).

FIG. 82 is a spectra 132030 of an ultrasonic device with a variety ofdifferent states and conditions of the end effector where the impedanceZ_(g)(t), magnitude |Z|, and phase cp are plotted as a function offrequency f, in accordance with at least one aspect of the presentdisclosure. The spectra 132030 is plotted in three-dimensional spacewhere frequency (Hz) is plotted along the x-axis, phase (Rad) is plottedalong the y-axis, and magnitude (Ohms) is plotted along the z-axis.

Spectral analysis of different jaw bites and device states producesdifferent complex impedance characteristic patterns (fingerprints)across a range of frequencies for different conditions and states. Eachstate or condition has a different characteristic pattern in 3D spacewhen plotted. These characteristic patterns can be used to estimate thecondition and state of the end effector. FIG. 82 shows the spectra forair 132032, clamp arm pad 132034, chamois 132036, staple 132038, andbroken blade 132040. The chamois 132036 may be used to characterizedifferent types of tissue.

The spectra 132030 can be evaluated by applying a low-power electricalsignal across the ultrasonic transducer to produce a non-therapeuticexcitation of the ultrasonic blade. The low-power electrical signal canbe applied in the form of a sweep or a compound Fourier series tomeasure the impedance

${Z_{g}(t)} = \frac{V_{g}(t)}{I_{g}(t)}$

across the ultrasonic transducer at a range of frequencies in series(sweep) or in parallel (compound signal) using an FFT.

Methods of Classification of New Data

For each characteristic pattern, a parametric line can be fit to thedata used for training using a polynomial, a Fourier series, or anyother form of parametric equation as may be dictated by convenience. Anew data point is then received and is classified by using the Euclideanperpendicular distance from the new data point to the trajectory thathas been fitted to the characteristic pattern training data. Theperpendicular distance of the new data point to each of the trajectories(each trajectory representing a different state or condition) is used toassign the point to a state or condition.

The probability distribution of distance of each point in the trainingdata to the fitted curve can be used to estimate the probability of acorrectly classified new data point. This essentially constructs atwo-dimensional probability distribution in a plane perpendicular to thefitted trajectory at each new data point of the fitted trajectory. Thenew data point can then be included in the training set based on itsprobability of correct classification to make an adaptive, learningclassifier that readily detects high-frequency changes in states butadapts to slow occurring deviations in system performance, such as adevice getting dirty or the pad wearing out.

FIG. 83 is a graphical representation of a plot 132042 of a set of 3Dtraining data set (S), where ultrasonic transducer impedance Z_(g)(t),magnitude |Z|, and phase cp are plotted as a function of frequency f, inaccordance with at least one aspect of the present disclosure. The 3Dtraining data set (S) plot 132042 is graphically depicted inthree-dimensional space where phase (Rad) is plotted along the x-axis,frequency (Hz) is plotted along the y-axis, magnitude (Ohms) is plottedalong the z-axis, and a parametric Fourier series is fit to the 3Dtraining data set (S). A methodology for classifying data is based onthe 3D training data set (S0 is used to generate the plot 132042).

The parametric Fourier series fit to the 3D training data set (S) isgiven by:

$\overset{\rightharpoonup}{p} = {{\overset{\rightharpoonup}{a}}_{0} + {\sum\limits_{n = 1}^{\infty}\left( {{{\overset{\rightharpoonup}{a}}_{n}\cos \frac{n\; \pi \; t}{L}} + {{\overset{\rightharpoonup}{b}}_{n}\sin \frac{n\; \pi \; t}{L}}} \right)}}$

For a new point {right arrow over (z)}, the perpendicular distance from{right arrow over (p)} to {right arrow over (z)} is found by:

D=∥{right arrow over (p)}−{right arrow over (z)}∥

When:

$\frac{\partial D}{\partial T} = 0$

Then:

D=D_(⊥)

A probability distribution of D can be used to estimate the probabilityof a data point {right arrow over (z)} belonging to the group S.

Control

Based on the classification of data measured before, during, or afteractivation of the ultrasonic transducer/ultrasonic blade, a variety ofautomated tasks and safety measures can be implemented. Similarly, thestate of the tissue located in the end effector and temperature of theultrasonic blade also can be inferred to some degree, and used to betterinform the user of the state of the ultrasonic device or protectcritical structures, etc. Temperature control of an ultrasonic blade isdescribed in commonly owned U.S. Provisional Patent Application No.62/640,417, filed Mar. 8, 2018, titled TEMPERATURE CONTROL IN ULTRASONICDEVICE AND CONTROL SYSTEM THEREFOR, which is incorporated herein byreference in its entirety.

Similarly, power delivery can be reduced when there is a highprobability that the ultrasonic blade is contacting the clamp arm pad(e.g., without tissue in between) or if there is a probability that theultrasonic blade has broken or that the ultrasonic blade is touchingmetal (e.g., a staple). Furthermore, back-cutting can be disallowed ifthe jaw is closed and no tissue is detected between the ultrasonic bladeand the clamp arm pad.

Integration of Other Data to Improve Classification

This system can be used in conjunction with other information providedby sensors, the user, metrics on the patient, environmental factors,etc., by combing the data from this process with the aforementioned datausing probability functions and a Kalman filter. The Kalman filterdetermines the maximum likelihood of a state or condition occurringgiven a plethora of uncertain measurements of varying confidence. Sincethis method allows for an assignment of probability to a newlyclassified data point, this algorithm's information can be implementedwith other measures or estimates in a Kalman filter.

FIG. 84 is a logic flow diagram 132044 depicting a control program or alogic configuration to determine jaw conditions based on the compleximpedance characteristic pattern (fingerprint), in accordance with atleast one aspect of the present disclosure. Prior to determining jawconditions based on the complex impedance characteristic pattern(fingerprint), a database is populated with reference complex impedancecharacteristic patterns or a training data sets (S) that characterizevarious jaw conditions, including, without limitation, air 132032, clamparm pad 132034, chamois 132036, staple 132038, broken blade 132040, asshown in FIG. 82, and a variety of tissue types and conditions. Thechamois dry or wet, full byte or tip, may be used to characterizedifferent types of tissue. The data points used to generate referencecomplex impedance characteristic patterns or a training data set (S) areobtained by applying a sub-therapeutic drive signal to the ultrasonictransducer, sweeping the driving frequency over a predetermined range offrequencies from below resonance to above resonance, measuring thecomplex impedance at each of the frequencies, and recording the datapoints. The data points are then fit to a curve using a variety ofnumerical methods including polynomial curve fit, Fourier series, and/orparametric equation. A parametric Fourier series fit to the referencecomplex impedance characteristic patterns or a training data set (S) isdescribed herein.

Once the reference complex impedance characteristic patterns or atraining data sets (S) are generated, the ultrasonic instrument measuresnew data points, classifies the new points, and determines whether thenew data points should be added to the reference complex impedancecharacteristic patterns or a training data sets (S).

Turning now to the logic flow diagram of FIG. 84, in one aspect, theprocessor or control circuit measures 132046 a complex impedance of anultrasonic transducer, wherein the complex impedance is defined as

${Z_{g}(t)} = {\frac{V_{g}(t)}{I_{g}(t)}.}$

The processor or control circuit receives 132048 a complex impedancemeasurement data point and compares 132050 the complex impedancemeasurement data point to a data point in a reference complex impedancecharacteristic pattern. The processor or control circuit classifies132052 the complex impedance measurement data point based on a result ofthe comparison analysis and assigns 132054 a state or condition of theend effector based on the result of the comparison analysis.

In one aspect, the processor or control circuit receives the referencecomplex impedance characteristic pattern from a database or memorycoupled to the processor. In one aspect, the processor or controlcircuit generates the reference complex impedance characteristic patternas follows. A drive circuit coupled to the processor or control circuitapplies a nontherapeutic drive signal to the ultrasonic transducerstarting at an initial frequency, ending at a final frequency, and at aplurality of frequencies therebetween. The processor or control circuitmeasures the impedance of the ultrasonic transducer at each frequencyand stores a data point corresponding to each impedance measurement. Theprocessor or control circuit curve fits a plurality of data points togenerate a three-dimensional curve of representative of the referencecomplex impedance characteristic pattern, wherein the magnitude |Z| andphase cp are plotted as a function of frequency f. The curve fittingincludes a polynomial curve fit, a Fourier series, and/or a parametricequation.

In one aspect, the processor or control circuit receives a new impedancemeasurement data point and classifies the new impedance measurement datapoint using a Euclidean perpendicular distance from the new impedancemeasurement data point to a trajectory that has been fitted to thereference complex impedance characteristic pattern. The processor orcontrol circuit estimates a probability that the new impedancemeasurement data point is correctly classified. The processor or controlcircuit adds the new impedance measurement data point to the referencecomplex impedance characteristic pattern based on the probability of theestimated correct classification of the new impedance measurement datapoint. In one aspect, the processor or control circuit classifies databased on a training data set (S), where the training data set (S)comprises a plurality of complex impedance measurement data, and curvefits the training data set (S) using a parametric Fourier series,wherein S is defined herein and wherein the probability distribution isused to estimate the probability of the new impedance measurement datapoint belonging to the group S.

Additional details regarding determining or estimating a state of thejaws or the surgical instrument as a whole can be found in U.S.Provisional Patent Application No. 62/692,768, titled SMART ENERGYDEVICES.

Situational Awareness

Referring now to FIG. 85, a timeline 5200 depicting situationalawareness of a hub, such as the surgical hub 106 or 206 (FIGS. 1-11),for example, is depicted. The timeline 5200 is an illustrative surgicalprocedure and the contextual information that the surgical hub 106, 206can derive from the data received from the data sources at each step inthe surgical procedure. The timeline 5200 depicts the typical steps thatwould be taken by the nurses, surgeons, and other medical personnelduring the course of a lung segmentectomy procedure, beginning withsetting up the operating theater and ending with transferring thepatient to a post-operative recovery room.

The situationally aware surgical hub 106, 206 receives data from thedata sources throughout the course of the surgical procedure, includingdata generated each time medical personnel utilize a modular device thatis paired with the surgical hub 106, 206. The surgical hub 106, 206 canreceive this data from the paired modular devices and other data sourcesand continually derive inferences (i.e., contextual information) aboutthe ongoing procedure as new data is received, such as which step of theprocedure is being performed at any given time. The situationalawareness system of the surgical hub 106, 206 is able to, for example,record data pertaining to the procedure for generating reports, verifythe steps being taken by the medical personnel, provide data or prompts(e.g., via a display screen) that may be pertinent for the particularprocedural step, adjust modular devices based on the context (e.g.,activate monitors, adjust the field of view (FOV) of the medical imagingdevice, or change the energy level of an ultrasonic surgical instrumentor RF electrosurgical instrument), and take any other such actiondescribed above.

As the first step 5202 in this illustrative procedure, the hospitalstaff members retrieve the patient's EMR from the hospital's EMRdatabase. Based on select patient data in the EMR, the surgical hub 106,206 determines that the procedure to be performed is a thoracicprocedure.

Second step 5204, the staff members scan the incoming medical suppliesfor the procedure. The surgical hub 106, 206 cross-references thescanned supplies with a list of supplies that are utilized in varioustypes of procedures and confirms that the mix of supplies corresponds toa thoracic procedure. Further, the surgical hub 106, 206 is also able todetermine that the procedure is not a wedge procedure (because theincoming supplies either lack certain supplies that are necessary for athoracic wedge procedure or do not otherwise correspond to a thoracicwedge procedure).

Third step 5206, the medical personnel scan the patient band via ascanner that is communicably connected to the surgical hub 106, 206. Thesurgical hub 106, 206 can then confirm the patient's identity based onthe scanned data.

Fourth step 5208, the medical staff turns on the auxiliary equipment.The auxiliary equipment being utilized can vary according to the type ofsurgical procedure and the techniques to be used by the surgeon, but inthis illustrative case they include a smoke evacuator, insufflator, andmedical imaging device. When activated, the auxiliary equipment that aremodular devices can automatically pair with the surgical hub 106, 206that is located within a particular vicinity of the modular devices aspart of their initialization process. The surgical hub 106, 206 can thenderive contextual information about the surgical procedure by detectingthe types of modular devices that pair with it during this pre-operativeor initialization phase. In this particular example, the surgical hub106, 206 determines that the surgical procedure is a VATS procedurebased on this particular combination of paired modular devices. Based onthe combination of the data from the patient's EMR, the list of medicalsupplies to be used in the procedure, and the type of modular devicesthat connect to the hub, the surgical hub 106, 206 can generally inferthe specific procedure that the surgical team will be performing. Oncethe surgical hub 106, 206 knows what specific procedure is beingperformed, the surgical hub 106, 206 can then retrieve the steps of thatprocedure from a memory or from the cloud and then cross-reference thedata it subsequently receives from the connected data sources (e.g.,modular devices and patient monitoring devices) to infer what step ofthe surgical procedure the surgical team is performing.

Fifth step 5210, the staff members attach the EKG electrodes and otherpatient monitoring devices to the patient. The EKG electrodes and otherpatient monitoring devices are able to pair with the surgical hub 106,206. As the surgical hub 106, 206 begins receiving data from the patientmonitoring devices, the surgical hub 106, 206 thus confirms that thepatient is in the operating theater.

Sixth step 5212, the medical personnel induce anesthesia in the patient.The surgical hub 106, 206 can infer that the patient is under anesthesiabased on data from the modular devices and/or patient monitoringdevices, including EKG data, blood pressure data, ventilator data, orcombinations thereof, for example. Upon completion of the sixth step5212, the pre-operative portion of the lung segmentectomy procedure iscompleted and the operative portion begins.

Seventh step 5214, the patient's lung that is being operated on iscollapsed (while ventilation is switched to the contralateral lung). Thesurgical hub 106, 206 can infer from the ventilator data that thepatient's lung has been collapsed, for example. The surgical hub 106,206 can infer that the operative portion of the procedure has commencedas it can compare the detection of the patient's lung collapsing to theexpected steps of the procedure (which can be accessed or retrievedpreviously) and thereby determine that collapsing the lung is the firstoperative step in this particular procedure.

Eighth step 5216, the medical imaging device (e.g., a scope) is insertedand video from the medical imaging device is initiated. The surgical hub106, 206 receives the medical imaging device data (i.e., video or imagedata) through its connection to the medical imaging device. Upon receiptof the medical imaging device data, the surgical hub 106, 206 candetermine that the laparoscopic portion of the surgical procedure hascommenced. Further, the surgical hub 106, 206 can determine that theparticular procedure being performed is a segmentectomy, as opposed to alobectomy (note that a wedge procedure has already been discounted bythe surgical hub 106, 206 based on data received at the second step 5204of the procedure). The data from the medical imaging device 124 (FIG. 2)can be utilized to determine contextual information regarding the typeof procedure being performed in a number of different ways, including bydetermining the angle at which the medical imaging device is orientedwith respect to the visualization of the patient's anatomy, monitoringthe number or medical imaging devices being utilized (i.e., that areactivated and paired with the surgical hub 106, 206), and monitoring thetypes of visualization devices utilized. For example, one technique forperforming a VATS lobectomy places the camera in the lower anteriorcorner of the patient's chest cavity above the diaphragm, whereas onetechnique for performing a VATS segmentectomy places the camera in ananterior intercostal position relative to the segmental fissure. Usingpattern recognition or machine learning techniques, for example, thesituational awareness system can be trained to recognize the positioningof the medical imaging device according to the visualization of thepatient's anatomy. As another example, one technique for performing aVATS lobectomy utilizes a single medical imaging device, whereas anothertechnique for performing a VATS segmentectomy utilizes multiple cameras.As yet another example, one technique for performing a VATSsegmentectomy utilizes an infrared light source (which can becommunicably coupled to the surgical hub as part of the visualizationsystem) to visualize the segmental fissure, which is not utilized in aVATS lobectomy. By tracking any or all of this data from the medicalimaging device, the surgical hub 106, 206 can thereby determine thespecific type of surgical procedure being performed and/or the techniquebeing used for a particular type of surgical procedure.

Ninth step 5218, the surgical team begins the dissection step of theprocedure. The surgical hub 106, 206 can infer that the surgeon is inthe process of dissecting to mobilize the patient's lung because itreceives data from the RF or ultrasonic generator indicating that anenergy instrument is being fired. The surgical hub 106, 206 cancross-reference the received data with the retrieved steps of thesurgical procedure to determine that an energy instrument being fired atthis point in the process (i.e., after the completion of the previouslydiscussed steps of the procedure) corresponds to the dissection step. Incertain instances, the energy instrument can be an energy tool mountedto a robotic arm of a robotic surgical system.

Tenth step 5220, the surgical team proceeds to the ligation step of theprocedure. The surgical hub 106, 206 can infer that the surgeon isligating arteries and veins because it receives data from the surgicalstapling and cutting instrument indicating that the instrument is beingfired. Similarly to the prior step, the surgical hub 106, 206 can derivethis inference by cross-referencing the receipt of data from thesurgical stapling and cutting instrument with the retrieved steps in theprocess. In certain instances, the surgical instrument can be a surgicaltool mounted to a robotic arm of a robotic surgical system.

Eleventh step 5222, the segmentectomy portion of the procedure isperformed. The surgical hub 106, 206 can infer that the surgeon istransecting the parenchyma based on data from the surgical stapling andcutting instrument, including data from its cartridge. The cartridgedata can correspond to the size or type of staple being fired by theinstrument, for example. As different types of staples are utilized fordifferent types of tissues, the cartridge data can thus indicate thetype of tissue being stapled and/or transected. In this case, the typeof staple being fired is utilized for parenchyma (or other similartissue types), which allows the surgical hub 106, 206 to infer that thesegmentectomy portion of the procedure is being performed.

Twelfth step 5224, the node dissection step is then performed. Thesurgical hub 106, 206 can infer that the surgical team is dissecting thenode and performing a leak test based on data received from thegenerator indicating that an RF or ultrasonic instrument is being fired.For this particular procedure, an RF or ultrasonic instrument beingutilized after parenchyma was transected corresponds to the nodedissection step, which allows the surgical hub 106, 206 to make thisinference. It should be noted that surgeons regularly switch back andforth between surgical stapling/cutting instruments and surgical energy(i.e., RF or ultrasonic) instruments depending upon the particular stepin the procedure because different instruments are better adapted forparticular tasks. Therefore, the particular sequence in which thestapling/cutting instruments and surgical energy instruments are usedcan indicate what step of the procedure the surgeon is performing.Moreover, in certain instances, robotic tools can be utilized for one ormore steps in a surgical procedure and/or handheld surgical instrumentscan be utilized for one or more steps in the surgical procedure. Thesurgeon(s) can alternate between robotic tools and handheld surgicalinstruments and/or can use the devices concurrently, for example. Uponcompletion of the twelfth step 5224, the incisions are closed up and thepost-operative portion of the procedure begins.

Thirteenth step 5226, the patient's anesthesia is reversed. The surgicalhub 106, 206 can infer that the patient is emerging from the anesthesiabased on the ventilator data (i.e., the patient's breathing rate beginsincreasing), for example.

Lastly, the fourteenth step 5228 is that the medical personnel removethe various patient monitoring devices from the patient. The surgicalhub 106, 206 can thus infer that the patient is being transferred to arecovery room when the hub loses EKG, BP, and other data from thepatient monitoring devices. As can be seen from the description of thisillustrative procedure, the surgical hub 106, 206 can determine or inferwhen each step of a given surgical procedure is taking place accordingto data received from the various data sources that are communicablycoupled to the surgical hub 106, 206.

Situational awareness is further described in U.S. Provisional PatentApplication Serial No. 62/659,900, titled METHOD OF HUB COMMUNICATION,filed Apr. 19, 2018, which is herein incorporated by reference in itsentirety. In certain instances, operation of a robotic surgical system,including the various robotic surgical systems disclosed herein, forexample, can be controlled by the hub 106, 206 based on its situationalawareness and/or feedback from the components thereof and/or based oninformation from the cloud 102.

While several forms have been illustrated and described, it is not theintention of the applicant to restrict or limit the scope of theappended claims to such detail. Numerous modifications, variations,changes, substitutions, combinations, and equivalents to those forms maybe implemented and will occur to those skilled in the art withoutdeparting from the scope of the present disclosure. Moreover, thestructure of each element associated with the described forms can bealternatively described as a means for providing the function performedby the element. Also, where materials are disclosed for certaincomponents, other materials may be used. It is therefore to beunderstood that the foregoing description and the appended claims areintended to cover all such modifications, combinations, and variationsas falling within the scope of the disclosed forms. The appended claimsare intended to cover all such modifications, variations, changes,substitutions, modifications, and equivalents.

The foregoing detailed description has set forth various forms of thedevices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beunderstood by those within the art that each function and/or operationwithin such block diagrams, flowcharts, and/or examples can beimplemented, individually and/or collectively, by a wide range ofhardware, software, firmware, or virtually any combination thereof.Those skilled in the art will recognize that some aspects of the formsdisclosed herein, in whole or in part, can be equivalently implementedin integrated circuits, as one or more computer programs running on oneor more computers (e.g., as one or more programs running on one or morecomputer systems), as one or more programs running on one or moreprocessors (e.g., as one or more programs running on one or moremicroprocessors), as firmware, or as virtually any combination thereof,and that designing the circuitry and/or writing the code for thesoftware and or firmware would be well within the skill of one of skillin the art in light of this disclosure. In addition, those skilled inthe art will appreciate that the mechanisms of the subject matterdescribed herein are capable of being distributed as one or more programproducts in a variety of forms, and that an illustrative form of thesubject matter described herein applies regardless of the particulartype of signal bearing medium used to actually carry out thedistribution.

Instructions used to program logic to perform various disclosed aspectscan be stored within a memory in the system, such as dynamic randomaccess memory (DRAM), cache, flash memory, or other storage.Furthermore, the instructions can be distributed via a network or by wayof other computer readable media. Thus a machine-readable medium mayinclude any mechanism for storing or transmitting information in a formreadable by a machine (e.g., a computer), but is not limited to, floppydiskettes, optical disks, compact disc, read-only memory (CD-ROMs), andmagneto-optical disks, read-only memory (ROMs), random access memory(RAM), erasable programmable read-only memory (EPROM), electricallyerasable programmable read-only memory (EEPROM), magnetic or opticalcards, flash memory, or a tangible, machine-readable storage used in thetransmission of information over the Internet via electrical, optical,acoustical or other forms of propagated signals (e.g., carrier waves,infrared signals, digital signals, etc.). Accordingly, thenon-transitory computer-readable medium includes any type of tangiblemachine-readable medium suitable for storing or transmitting electronicinstructions or information in a form readable by a machine (e.g., acomputer).

As used in any aspect herein, the term “control circuit” may refer to,for example, hardwired circuitry, programmable circuitry (e.g., acomputer processor comprising one or more individual instructionprocessing cores, processing unit, processor, microcontroller,microcontroller unit, controller, digital signal processor (DSP),programmable logic device (PLD), programmable logic array (PLA), orfield programmable gate array (FPGA)), state machine circuitry, firmwarethat stores instructions executed by programmable circuitry, and anycombination thereof. The control circuit may, collectively orindividually, be embodied as circuitry that forms part of a largersystem, for example, an integrated circuit (IC), an application-specificintegrated circuit (ASIC), a system on-chip (SoC), desktop computers,laptop computers, tablet computers, servers, smart phones, etc.Accordingly, as used herein “control circuit” includes, but is notlimited to, electrical circuitry having at least one discrete electricalcircuit, electrical circuitry having at least one integrated circuit,electrical circuitry having at least one application specific integratedcircuit, electrical circuitry forming a general purpose computing deviceconfigured by a computer program (e.g., a general purpose computerconfigured by a computer program which at least partially carries outprocesses and/or devices described herein, or a microprocessorconfigured by a computer program which at least partially carries outprocesses and/or devices described herein), electrical circuitry forminga memory device (e.g., forms of random access memory), and/or electricalcircuitry forming a communications device (e.g., a modem, communicationsswitch, or optical-electrical equipment). Those having skill in the artwill recognize that the subject matter described herein may beimplemented in an analog or digital fashion or some combination thereof.

As used in any aspect herein, the term “logic” may refer to an app,software, firmware and/or circuitry configured to perform any of theaforementioned operations. Software may be embodied as a softwarepackage, code, instructions, instruction sets and/or data recorded onnon-transitory computer readable storage medium. Firmware may beembodied as code, instructions or instruction sets and/or data that arehard-coded (e.g., nonvolatile) in memory devices.

As used in any aspect herein, the terms “component,” “system,” “module”and the like can refer to a computer-related entity, either hardware, acombination of hardware and software, software, or software inexecution.

As used in any aspect herein, an “algorithm” refers to a self-consistentsequence of steps leading to a desired result, where a “step” refers toa manipulation of physical quantities and/or logic states which may,though need not necessarily, take the form of electrical or magneticsignals capable of being stored, transferred, combined, compared, andotherwise manipulated. It is common usage to refer to these signals asbits, values, elements, symbols, characters, terms, numbers, or thelike. These and similar terms may be associated with the appropriatephysical quantities and are merely convenient labels applied to thesequantities and/or states.

A network may include a packet switched network. The communicationdevices may be capable of communicating with each other using a selectedpacket switched network communications protocol. One examplecommunications protocol may include an Ethernet communications protocolwhich may be capable permitting communication using a TransmissionControl Protocol/Internet Protocol (TCP/IP). The Ethernet protocol maycomply or be compatible with the Ethernet standard published by theInstitute of Electrical and Electronics Engineers (IEEE) titled “IEEE802.3 Standard”, published in December, 2008 and/or later versions ofthis standard. Alternatively or additionally, the communication devicesmay be capable of communicating with each other using an X.25communications protocol. The X.25 communications protocol may comply orbe compatible with a standard promulgated by the InternationalTelecommunication Union-Telecommunication Standardization Sector(ITU-T). Alternatively or additionally, the communication devices may becapable of communicating with each other using a frame relaycommunications protocol. The frame relay communications protocol maycomply or be compatible with a standard promulgated by ConsultativeCommittee for International Telegraph and Telephone (CCITT) and/or theAmerican National Standards Institute (ANSI). Alternatively oradditionally, the transceivers may be capable of communicating with eachother using an Asynchronous Transfer Mode (ATM) communications protocol.The ATM communications protocol may comply or be compatible with an ATMstandard published by the ATM Forum titled “ATM-MPLS NetworkInterworking 2.0” published August 2001, and/or later versions of thisstandard. Of course, different and/or after-developedconnection-oriented network communication protocols are equallycontemplated herein.

Unless specifically stated otherwise as apparent from the foregoingdisclosure, it is appreciated that, throughout the foregoing disclosure,discussions using terms such as “processing,” “computing,”“calculating,” “determining,” “displaying,” or the like, refer to theaction and processes of a computer system, or similar electroniccomputing device, that manipulates and transforms data represented asphysical (electronic) quantities within the computer system's registersand memories into other data similarly represented as physicalquantities within the computer system memories or registers or othersuch information storage, transmission or display devices.

One or more components may be referred to herein as “configured to,”“configurable to,” “operable/operative to,” “adapted/adaptable,” “ableto,” “conformable/conformed to,” etc. Those skilled in the art willrecognize that “configured to” can generally encompass active-statecomponents and/or inactive-state components and/or standby-statecomponents, unless context requires otherwise.

The terms “proximal” and “distal” are used herein with reference to aclinician manipulating the handle portion of the surgical instrument.The term “proximal” refers to the portion closest to the clinician andthe term “distal” refers to the portion located away from the clinician.It will be further appreciated that, for convenience and clarity,spatial terms such as “vertical”, “horizontal”, “up”, and “down” may beused herein with respect to the drawings. However, surgical instrumentsare used in many orientations and positions, and these terms are notintended to be limiting and/or absolute.

Those skilled in the art will recognize that, in general, terms usedherein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to claims containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations.

In addition, even if a specific number of an introduced claim recitationis explicitly recited, those skilled in the art will recognize that suchrecitation should typically be interpreted to mean at least the recitednumber (e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to “at least one of A, B, or C, etc.” is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, or C” would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that typically a disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms unless context dictates otherwise. For example, the phrase “Aor B” will be typically understood to include the possibilities of “A”or “B” or “A and B.”

With respect to the appended claims, those skilled in the art willappreciate that recited operations therein may generally be performed inany order. Also, although various operational flow diagrams arepresented in a sequence(s), it should be understood that the variousoperations may be performed in other orders than those which areillustrated, or may be performed concurrently. Examples of suchalternate orderings may include overlapping, interleaved, interrupted,reordered, incremental, preparatory, supplemental, simultaneous,reverse, or other variant orderings, unless context dictates otherwise.Furthermore, terms like “responsive to,” “related to,” or otherpast-tense adjectives are generally not intended to exclude suchvariants, unless context dictates otherwise.

It is worthy to note that any reference to “one aspect,” “an aspect,”“an exemplification,” “one exemplification,” and the like means that aparticular feature, structure, or characteristic described in connectionwith the aspect is included in at least one aspect. Thus, appearances ofthe phrases “in one aspect,” “in an aspect,” “in an exemplification,”and “in one exemplification” in various places throughout thespecification are not necessarily all referring to the same aspect.Furthermore, the particular features, structures or characteristics maybe combined in any suitable manner in one or more aspects.

Any patent application, patent, non-patent publication, or otherdisclosure material referred to in this specification and/or listed inany Application Data Sheet is incorporated by reference herein, to theextent that the incorporated materials is not inconsistent herewith. Assuch, and to the extent necessary, the disclosure as explicitly setforth herein supersedes any conflicting material incorporated herein byreference. Any material, or portion thereof, that is said to beincorporated by reference herein, but which conflicts with existingdefinitions, statements, or other disclosure material set forth hereinwill only be incorporated to the extent that no conflict arises betweenthat incorporated material and the existing disclosure material.

In summary, numerous benefits have been described which result fromemploying the concepts described herein. The foregoing description ofthe one or more forms has been presented for purposes of illustrationand description. It is not intended to be exhaustive or limiting to theprecise form disclosed. Modifications or variations are possible inlight of the above teachings. The one or more forms were chosen anddescribed in order to illustrate principles and practical application tothereby enable one of ordinary skill in the art to utilize the variousforms and with various modifications as are suited to the particular usecontemplated. It is intended that the claims submitted herewith definethe overall scope.

Various aspects of the subject matter described herein are set out inthe following numbered examples:

EXAMPLE 1

An ultrasonic surgical instrument comprising: an end effector comprisingan ultrasonic blade, an ultrasonic transducer acoustically coupled tothe ultrasonic blade, and a control circuit coupled to the ultrasonictransducer. The ultrasonic transducer is configured to ultrasonicallyoscillate the ultrasonic blade in response to a drive signal. Thecontrol circuit is configured to: measure a complex impedance of theultrasonic transducer, compare the complex impedance to a plurality ofreference complex impedance patterns, each of the plurality of referencecomplex impedance patterns corresponding to a state of the end effector,and determine the state of the end effector according to which of theplurality of reference complex impedance patterns the complex impedancecorresponds.

EXAMPLE 2

The ultrasonic surgical instrument of Example 1, wherein the pluralityof reference complex impedance patterns correspond to at least one ofthe ultrasonic blade contacting air, the ultrasonic blade being broken,or the ultrasonic blade contacting metal.

EXAMPLE 3

The ultrasonic surgical instrument of Example 1 or 2, further comprisinga memory coupled to the control circuit. The memory stores the pluralityof reference complex impedance patterns. The control circuit isconfigured to retrieve the plurality of reference complex impedancepatterns from the memory.

EXAMPLE 4

The ultrasonic surgical instrument of any one of Examples 1-3, whereinthe reference complex impedance patterns comprise fitted curves plottedfrom data points of the reference complex impedance patterns.

EXAMPLE 5

The ultrasonic surgical instrument of Example 4, wherein the controlcircuit is configured to determine which of the plurality of referencecomplex impedance patterns the complex impedance corresponds accordingto a Euclidean perpendicular distance between the complex impedance andthe fitted curves.

EXAMPLE 6

The ultrasonic surgical instrument of Example 5, wherein the compleximpedance corresponds to which of the fitted curves the compleximpedance has a smallest Euclidean perpendicular distance therebetween.

EXAMPLE 7

The ultrasonic surgical instrument of any one of Examples 1-6, whereinthe complex impedance corresponds to a ratio between a voltage signaland a current signal exciting the ultrasonic transducer.

EXAMPLE 8

An ultrasonic generator for driving an ultrasonic surgical instrumentcomprising an end effector, an ultrasonic blade, and an ultrasonictransducer acoustically coupled to the ultrasonic blade. The ultrasonictransducer is configured to ultrasonically oscillate the ultrasonicblade in response to a drive signal. The ultrasonic generator comprisesa control circuit coupled to the ultrasonic transducer. The controlcircuit is configured to: apply the drive signal to the ultrasonictransducer, measure a complex impedance of the ultrasonic transducer,compare the complex impedance to a plurality of reference compleximpedance patterns, each of the plurality of reference complex impedancepatterns corresponding to a state of the end effector, and determine thestate of the end effector according to which of the plurality ofreference complex impedance patterns the complex impedance corresponds.

EXAMPLE 9

The ultrasonic generator of Example 8, wherein the plurality ofreference complex impedance patterns correspond to at least one of theultrasonic blade contacting air, the ultrasonic blade being broken, orthe ultrasonic blade contacting metal.

EXAMPLE 10

The ultrasonic generator of Example 8 or 9, further comprising a memorycoupled to the control circuit. The memory stores the plurality ofreference complex impedance patterns. The control circuit is configuredto retrieve the plurality of reference complex impedance patterns fromthe memory.

EXAMPLE 11

The ultrasonic generator of at least one of Examples 8-10, wherein thereference complex impedance patterns comprise fitted curves plotted fromdata points of the reference complex impedance patterns.

EXAMPLE 12

The ultrasonic generator of Example 11, wherein the control circuit isconfigured to determine which of the plurality of reference compleximpedance patterns the complex impedance corresponds according to aEuclidean perpendicular distance between the complex impedance and thefitted curves.

EXAMPLE 13

The ultrasonic generator of Example 12, wherein the complex impedancecorresponds to which of the fitted curves the complex impedance has asmallest Euclidean perpendicular distance therebetween.

EXAMPLE 14

The ultrasonic generator of any one of Examples 8-13, wherein thecomplex impedance corresponds to a ratio between a voltage signal and acurrent signal exciting the ultrasonic transducer.

EXAMPLE 15

A method of controlling an ultrasonic surgical instrument comprising anend effector, an ultrasonic blade, and an ultrasonic transduceracoustically coupled to the ultrasonic blade. The ultrasonic transduceris configured to ultrasonically oscillate the ultrasonic blade inresponse to a drive signal from a generator. The method comprises:measuring, by a control circuit coupled to the ultrasonic transducer, acomplex impedance of the ultrasonic transducer; comparing, by thecontrol circuit, the complex impedance to a plurality of referencecomplex impedance patterns, each of the plurality of reference compleximpedance patterns corresponding to a state of the end effector; anddetermining, by the control circuit, the state of the end effectoraccording to which of the plurality of reference complex impedancepatterns the complex impedance corresponds.

EXAMPLE 16

The method of Example 15, wherein the plurality of reference compleximpedance patterns correspond to at least one of the ultrasonic bladecontacting air, the ultrasonic blade being broken, or the ultrasonicblade contacting metal.

EXAMPLE 17

The method of Example 15 or 16, further comprising retrieving, by thecontrol circuit, the plurality of reference complex impedance patternsfrom a memory.

EXAMPLE 18

The method of any one of Examples 15-17, wherein the reference compleximpedance patterns comprise fitted curves plotted from data points ofthe reference complex impedance patterns.

EXAMPLE 19

The method of Example 18, further comprising determining, by the controlcircuit, which of the plurality of reference complex impedance patternsthe complex impedance corresponds according to a Euclidean perpendiculardistance between the complex impedance and the fitted curves.

EXAMPLE 20

The method of Example 19, wherein the complex impedance corresponds towhich of the fitted curves the complex impedance has a smallestEuclidean perpendicular distance therebetween.

EXAMPLE 21

The method of any one of Examples 15-20, wherein the complex impedancecorresponds to a ratio between a voltage signal and a current signalexciting the ultrasonic transducer.

1. An ultrasonic surgical instrument comprising: an end effectorcomprising an ultrasonic blade; an ultrasonic transducer acousticallycoupled to the ultrasonic blade, the ultrasonic transducer configured toultrasonically oscillate the ultrasonic blade in response to a drivesignal; and a control circuit coupled to the ultrasonic transducer, thecontrol circuit configured to: measure a complex impedance of theultrasonic transducer; compare the complex impedance to a plurality ofreference complex impedance patterns, each of the plurality of referencecomplex impedance patterns corresponding to a state of the end effector;and determine the state of the end effector according to which of theplurality of reference complex impedance patterns the complex impedancecorresponds.
 2. The ultrasonic surgical instrument of claim 1, whereinthe plurality of reference complex impedance patterns correspond to atleast one of the ultrasonic blade contacting air, the ultrasonic bladebeing broken, or the ultrasonic blade contacting metal.
 3. Theultrasonic surgical instrument of claim 1, further comprising: a memorycoupled to the control circuit, the memory storing the plurality ofreference complex impedance patterns; wherein the control circuit isconfigured to retrieve the plurality of reference complex impedancepatterns from the memory.
 4. The ultrasonic surgical instrument of claim1, wherein the reference complex impedance patterns comprise fittedcurves plotted from data points of the reference complex impedancepatterns.
 5. The ultrasonic surgical instrument of claim 4, wherein thecontrol circuit is configured to determine which of the plurality ofreference complex impedance patterns the complex impedance correspondsaccording to a Euclidean perpendicular distance between the compleximpedance and the fitted curves.
 6. The ultrasonic surgical instrumentof claim 5, wherein the complex impedance corresponds to which of thefitted curves the complex impedance has a smallest Euclideanperpendicular distance therebetween.
 7. The ultrasonic surgicalinstrument of claim 1, wherein the complex impedance corresponds to aratio between a voltage signal and a current signal exciting theultrasonic transducer.
 8. An ultrasonic generator for driving anultrasonic surgical instrument comprising an end effector, an ultrasonicblade, and an ultrasonic transducer acoustically coupled to theultrasonic blade, the ultrasonic transducer configured to ultrasonicallyoscillate the ultrasonic blade in response to a drive signal, theultrasonic generator comprising: a control circuit coupled to theultrasonic transducer, the control circuit configured to: apply thedrive signal to the ultrasonic transducer; measure a complex impedanceof the ultrasonic transducer; compare the complex impedance to aplurality of reference complex impedance patterns, each of the pluralityof reference complex impedance patterns corresponding to a state of theend effector; and determine the state of the end effector according towhich of the plurality of reference complex impedance patterns thecomplex impedance corresponds.
 9. The ultrasonic generator of claim 8,wherein the plurality of reference complex impedance patterns correspondto at least one of the ultrasonic blade contacting air, the ultrasonicblade being broken, or the ultrasonic blade contacting metal.
 10. Theultrasonic generator of claim 8, further comprising: a memory coupled tothe control circuit, the memory storing the plurality of referencecomplex impedance patterns; wherein the control circuit is configured toretrieve the plurality of reference complex impedance patterns from thememory.
 11. The ultrasonic generator of claim 8, wherein the referencecomplex impedance patterns comprise fitted curves plotted from datapoints of the reference complex impedance patterns.
 12. The ultrasonicgenerator of claim 11, wherein the control circuit is configured todetermine which of the plurality of reference complex impedance patternsthe complex impedance corresponds according to a Euclidean perpendiculardistance between the complex impedance and the fitted curves.
 13. Theultrasonic generator of claim 12, wherein the complex impedancecorresponds to which of the fitted curves the complex impedance has asmallest Euclidean perpendicular distance therebetween.
 14. Theultrasonic generator of claim 8, wherein the complex impedancecorresponds to a ratio between a voltage signal and a current signalexciting the ultrasonic transducer.
 15. A method of controlling anultrasonic surgical instrument comprising an end effector, an ultrasonicblade, and an ultrasonic transducer acoustically coupled to theultrasonic blade, the ultrasonic transducer configured to ultrasonicallyoscillate the ultrasonic blade in response to a drive signal from agenerator, the method comprising: measuring, by a control circuitcoupled to the ultrasonic transducer, a complex impedance of theultrasonic transducer; comparing, by the control circuit, the compleximpedance to a plurality of reference complex impedance patterns, eachof the plurality of reference complex impedance patterns correspondingto a state of the end effector; and determining, by the control circuit,the state of the end effector according to which of the plurality ofreference complex impedance patterns the complex impedance corresponds.16. The method of claim 15, wherein the plurality of reference compleximpedance patterns correspond to at least one of the ultrasonic bladecontacting air, the ultrasonic blade being broken, or the ultrasonicblade contacting metal.
 17. The method of claim 15, further comprisingretrieving, by the control circuit, the plurality of reference compleximpedance patterns from a memory.
 18. The method of claim 15, whereinthe reference complex impedance patterns comprise fitted curves plottedfrom data points of the reference complex impedance patterns.
 19. Themethod of claim 18, further comprising determining, by the controlcircuit, which of the plurality of reference complex impedance patternsthe complex impedance corresponds according to a Euclidean perpendiculardistance between the complex impedance and the fitted curves.
 20. Themethod of claim 19, wherein the complex impedance corresponds to whichof the fitted curves the complex impedance has a smallest Euclideanperpendicular distance therebetween.
 21. The method of claim 15, whereinthe complex impedance corresponds to a ratio between a voltage signaland a current signal exciting the ultrasonic transducer.